Vedolizumab in the treatment of chronic, antibiotic-dependent or refractory pouchitis

BACKGROUND

The most common complication after ileal pouch anal anastomosis in up to 50% of patients is an acute pouchitis. The majority of patients respond to antibiotic treatment. However, 10%-15% develops chronic antibiotic-dependent or refractory pouchitis which is usually hard to treat.

AIM

To evaluate the effectiveness of vedolizumab in patients with chronic pouchitis.

METHODS

Patients with chronic antibiotic-dependent or refractory pouchitis were treated with vedolizumab (300 mg at week 0, 2, 6 and 10) in 10 IBD centres and retrospectively registered. Data were recorded until week 14 of vedolizumab treatment. In total 20 patients (12 male, median age 43 years) were included for analysis. The effectiveness was measured using the Oresland Score (OS) at week 2, 6, 10 and 14 and the pouch disease activity index (PDAI) at week 0 and 14.

RESULTS

The mean OS declined from 6.8 (range 2-12) to 3.4 (range 0-11). Concordantly, the mean PDAI after 14 weeks of treatment dropped from 10 (range 5-18) to 3 (range 0-10). Only three patients reported moderate side effects. No serious side effects were recorded. In addition, symptomatic co-medication such as loperamide and tincture of opium could be terminated in 8 out of 12 patients as well as antibiotic treatment could be stopped in 17 out of 19 patients.

CONCLUSION

Our data indicate that vedolizumab could be an option in the treatment of patients with chronic, antibiotic-dependent or refractory pouchitis.

Long-term Outcomes in Steroid-refractory Ulcerative Colitis Treated with Tacrolimus Alone or in Combination with Purine Analogues

BACKGROUND AND AIMS

Tacrolimus is recommended for the treatment of steroid-refractory ulcerative colitis (UC). Concomitantly started purine analogues (PAs) are used for the maintenance of remission, though their therapeutic relevance remains uncertain. Here we studied the role of PAs in the long-term outcome of steroid-refractory UC after tacrolimus treatment.

METHODS

In five centres, charts of tacrolimus-treated UC patients with a steroid-refractory moderate to severe course were reviewed. Long-term efficacy was determined by colectomy rates and clinical remission in cases of colectomy-free survival for 3 months.

RESULTS

We identified 156 patients (median age 34 years) with a median Lichtiger score of 12 (4-17) and pancolitis (E3) in 65% (101). The Kaplan-Meier curve for colectomy-free survival after month 3 showed a benefit in the PA group (p = 0.02). In patients treated with PA clinical remission was achieved in 82% (65/79) vs 67% (39/58) in those not treated with PA (p = 0.02). Time to colectomy was 2 years (median, 0.7-5.8) in the PA group and 0.8 years (0.3-4.7) in the group not treated with PAs (p = 0.02). Time to relapse was 1.2 years (median, 0.3-6.2) in patients with PA treatment and 0.5 years (0.3-3.9) in those without PA treatment (p = 0.05). Overall, clinical remission was achieved in 67% (104/156) of patients. Colectomy was performed in 29% (45/156) 0.5 years (median, 0.04-5.79) after initiation of tacrolimus. Ten (6%) patients had to stop tacrolimus due to adverse events and two (without PA treatment) died.

CONCLUSIONS

Our study supports the efficacy of tacrolimus in steroid-refractory UC. Purine analogues appear to be beneficial for the long-term outcome of these patients.

Benefit of Contrast-Enhanced Ultrasound (CEUS) in the Follow-Up Care of Patients with Colon Cancer: A Prospective Multicenter Study

PURPOSE

According to the German guidelines on colorectal cancer, unenhanced ultrasound is recommended for follow-up. On the other hand, ultrasound and radiology societies specify the use of contrast-enhanced ultrasound for ruling out liver metastases. Studies focusing on the follow-up of cancer patients are lacking. The goal of this multicenter study initiated by the German Ultrasound Society (DEGUM) was to determine the potential benefit of contrast-enhanced ultrasound in the follow-up of patients with colon cancer.

MATERIALS AND METHODS

Follow-up patients with colon cancer (UICC > IIa) were investigated. As scheduled according to the German guidelines, unenhanced ultrasound was performed followed by contrast-enhanced ultrasound. All liver lesions were recorded. In case of additional metastases detected on contrast-enhanced ultrasound, contrast-enhanced CT, MRI or biopsy was performed to confirm additional liver metastases.

RESULTS

A total of 45 liver metastases were detected in 26/290 patients (= 9 %) using unenhanced ultrasound. A further 28 metastases were detected on contrast-enhanced ultrasound in these 26 patients. In 18 patients showing no liver metastases, 40 additional metastases were detected on unenhanced ultrasound. This means that 44 patients with a total of 113 liver metastases were detected on contrast-enhanced ultrasound (p = 0.0006).

CONCLUSION

Contrast-enhanced ultrasound should be recommended in the follow-up of patients with colon cancer in addition to unenhanced ultrasound - the up-to-date standard.

Efficacy, safety and tolerability of vidofludimus in patients with inflammatory bowel disease: the ENTRANCE study

BACKGROUND

Vidofludimus (SC12267) is a novel oral immunomodulator inhibiting dihydroorotate dehydrogenase (DHODH) and the expression of proinflammatory cytokines including interleukin-17 (IL17A and IL17F) and interferon-gamma. The objective of the study was to explore the efficacy, safety and tolerability of vidofludimus in steroid-dependent inflammatory bowel disease (IBD).

METHODS

The open label uncontrolled ENTRANCE study (ClinicalTrials.gov NCT00820365) has been conducted at 13 study centers in Germany, Bulgaria and Romania. Thirty-four steroid-dependent patients with a confirmed diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) were treated with a once daily 35mg oral dose of vidofludimus over 12weeks. Steroids were tapered during the first 8weeks followed by a steroid-free treatment period of 4weeks. Complete response was defined as steroid-free clinical remission at week 12; partial response was defined as being in remission at steroid dose equal or lower than the individual patient's threshold dose for relapse.

RESULTS

Of the thirty-four patients enrolled in this trial 26 were evaluable for primary efficacy assessment. After completion of the 12weeks treatment phase 8 out of 14 (57.1%) patients with CD and 6 out of 12 (50.0%) patients with UC were in steroid-free remission (complete responders). Another 4 (28.6%) patients in CD and 5 (41.7%) patients in UC were partial responders. Vidofludimus was well tolerated, no drug-related serious adverse events were observed.

CONCLUSIONS

This trial provides first evidence of clinical efficacy of vidofludimus in IBD. Although the safety and tolerability profile seems favorable, long-term controlled studies are needed to further investigate its potential as novel IBD therapy.

Inflammatory bowel diseases influence major histocompatibility complex class I (MHC I) and II compartments in intestinal epithelial cells

Antigen presentation by intestinal epithelial cells (IEC) is crucial for intestinal homeostasis. Disturbances of major histocompatibility complex class I (MHC I)- and II-related presentation pathways in IEC appear to be involved in an altered activation of CD4(+) and CD8(+) T cells in inflammatory bowel disease. However, a comprehensive analysis of MHC I- and II-enriched compartments in IEC of the small and large bowel in the healthy state as opposed to inflammatory bowel diseases is lacking. The aim of this study was to characterize the subcellular expression of MHC I and II in the endocytic pathway of IEC throughout all parts of the intestinal tract, and to identify differences between the healthy state and inflammatory bowel diseases. Biopsies were taken by endoscopy from the duodenum, jejunum, ileum and colon in healthy individuals (n = 20). In Crohn's disease (CD), biopsies were obtained from the ileum and colon and within the colon from ulcerative colitis (UC) patients (n = 15). Analysis of IEC was performed by immunoelectron microscopy. MHC I and II were identified in early endosomes and multi-vesicular, multi-lamellar, electrondense and vacuolar late endosomes. Both molecules were enriched in multi-vesicular bodies. No differences were found between the distinct parts of the gut axis. In CD and UC the expression of MHC I and II showed a shift from multi-vesicular bodies towards the basolateral membranes. Within the multi-vesicular bodies, MHC I and II moved from internal vesicles to the limiting membranes upon inflammation in CD and UC. MHC I- and II-enriched compartments in IEC were identical in all parts of the small and large bowel. CD and UC appear to modulate the MHC I- and II-related presentation pathways of exogenous antigens in IEC.

Short-term efficacy of tacrolimus in steroid-refractory ulcerative colitis - experience in 130 patients

BACKGROUND

Steroid-refractory ulcerative colitis (UC) remains a challenging condition warranting surgery upon failure of pharmacological treatment. Calcineurin inhibitors or infliximab are alternatives in this situation. Data on the efficacy and safety of tacrolimus in this setting are limited.

AIM

To study the short-term efficacy and safety of tacrolimus in moderate-to-severe steroid-refractory UC. The role of thiopurines in this situation and predictors of colectomy were evaluated.

METHODS

In three centers, all charts from tacrolimus-treated patients with steroid-refractory UC were reviewed. Efficacy was assessed by colectomy-free survival and clinical remission at 3 months.

RESULTS

We identified 130 patients with pancolitis in 75 (59%), left-sided disease in 35 (27%) and proctitis in 18 patients (14%) (disease localisation not obtainable in two patients). The median age was 40 (range: 18-81). Clinical activity according to the median Lichtiger score decreased from 13 (range: 4-17) at baseline to 3 (0-14) at week 12. Eighteen patients underwent colectomy within the first 3 months of treatment with tacrolimus (14%). Clinical remission was achieved in 94 patients (72%) in this period. Thiopurines given in parallel to tacrolimus tended to limit colectomy and significantly increased remission (P = 0.002) in the short-term. No other predictors of colectomy or remission were identified. Side effects were noticed in 53% of patients and no severe events occurred.

CONCLUSION

This large survey confirms the efficacy and safety of tacrolimus in patients with steroid-refractory ulcerative colitis.

[CEUS as a tool to uncover an unusual cause of obstructive jaundice]

Aneurysms within the visceral arteries are rare. Among these, aneurysms of the splenic artery occur most frequently followed by aneurysms of the hepatic arteries. An early diagnosis is easily missed and almost all patients become symptomatic with an acute rupture associated with high mortality. Here we demonstrate the case of a 76-year-old patient who presented with acute upper abdominal pain accompanied by a single episode of vomiting and pyrexia of 39 °C. Laboratory results presented the picture of an obstructive jaundice without evidence for accompanying pancreatitis. Inflammatory markers were within normal limits at onset, but increased dramatically within the next few days. An acute calculous cholecystitis was diagnosed on abdominal ultrasound whereas gastroscopy revealed no relevant changes. Computed tomography was suspicious for pancreatitis of the head with obstruction of the bile duct. Choledocholithiasis was ruled out by ERCP, but symptoms persisted despite papillotomy. Due to raising inflammatory markers and an ongoing impairment of the patients condition, an abdominal CT scan was repeated which revealed the suspicion of a ruptured aneurysm of the common hepatic artery. At the time of transferral we were able to confirm the diagnosis by contrast-enhanced ultrasound and angiography. The patient was immediately forwarded to surgery due to lack of satisfactory endovascular procedures. In summary, the patient suffered from a ruptured spurial aneurysm of the right gastric artery thereby obstructing the common bile duct. Beside CT scans and angiography, this case documents a pivotal role for contrast-enhanced ultrasound in the work-up of visceral artery aneurysms.

Defensin-immunology in inflammatory bowel disease

Defensins are endogenous antibiotics with microbicidal activity against Gram-negative and Gram-positive bacteria, fungi, enveloped viruses and protozoa. A disturbed antimicrobial defense, as provided by Paneth- and other epithelial cell defensins, seems to be a critical factor in the pathogenesis of inflammatory bowel diseases. Conspicuously, there is a relative lack of Paneth cell beta-defensins HD-5 and HD-6 in ileal Crohn's disease, both in the absence of a pattern recognition receptor NOD2 mutation and, even more pronounced, in its presence. This deficit is independent of concurrent active inflammation and results in a diminished antibacterial killing by the mucosa. The Crohn's disease mucosa has not only a significant lack in killing different Escherichia coli but also an impaired ability in clearing Staphylococcus aureus as well as anaerobic micro-organisms. Thus, this dysfunction in antibacterial barrier seems to be broad and is not restricted to a single bacterial strain. In addition to directly controlling barrier function, Paneth cell defensins also regulate the composition of the bacterial stool flora. In the majority of patients, the Paneth cell deficiency is mediated by WNT signalling which suggests a disturbed Paneth cell differentiation in ileal Crohn's disease. In contrast, colonic Crohn's disease is characterised by an impaired induction of mucosal beta-defensins, partly due to a low copy number of the beta-defensin gene cluster. Therefore it seems plausible that bacteria take advantage of a niche formed by defensin deficiency. This would represent a paradigm shift in understanding Crohn's disease and provides a target for future therapeutic strategies.

Infliximab as rescue medication for patients with severe ulcerative/indeterminate colitis refractory to tacrolimus

BACKGROUND

The calcineurin inhibitor tacrolimus and the anti-TNF-antibody infliximab are established options in steroid-refractory ulcerative colitis (UC).

AIM

To evaluate the efficacy of infliximab-salvage therapy in patients with refractory UC failing to respond to tacrolimus.

METHODS

Twenty-four patients were enrolled in this evaluation. Reasons for tacrolimus therapy were steroid-refractory disease in 19 patients and steroid-dependency in five patients. All patients receiving infliximab had tacrolimus-refractory active disease (Lichtiger score >10) and were treated with 5 mg/kg at weeks 0, 2 and 6 and every 8 weeks thereafter, if tolerated.

RESULTS

Six of 24 patients (25%) achieved remission following infliximab infusion and four of 24 (17%) had an initial response only, but underwent proctocolectomy later because of loss of response (3) or development of a delayed hypersensitivity reaction (1). Fourteen patients (58%) completely failed to respond with 10 undergoing colectomy. Eight patients experienced side effects under infliximab, including two infectious complications (herpes zoster and herpes pneumonia).

CONCLUSIONS

Infliximab offers a therapeutic option as rescue therapy in about a quarter of patients with active UC after failing to respond to tacrolimus. This benefit has to be weighed against the risks of infectious complications.

Influence of standard treatment on ileal and colonic antimicrobial defensin expression in active Crohn's disease

BACKGROUND

Crohn's Disease (CD), a chronic intestinal inflammation, is currently treated primarily by therapeutics which are directed against inflammatory responses. Recent findings though suggest a central role of the innate immune barrier in the pathophysiology. Important factors providing this barrier are antimicrobial peptides like the alpha- and beta-defensins. Little is known about in vivo effects of common drugs on their expression.

AIM

To analyse the influence of corticosteroids, azathioprine and aminosalicylate treatment on ileal and colonic antimicrobial peptides in active CD and also assess the role of inflammation.

METHODS

We measured the expression of antimicrobial peptides and pro-inflammatory cytokines in 75 patients with active CD.

RESULTS

Ileal and colonic alpha- and beta-defensins as well as LL37 remained unaffected by corticosteroids, azathioprine or aminosalicylate treatment. Additionally, we did not observe a negative coherency between Paneth cell alpha-defensins and any measured cytokines. HBD2 and LL37 unlike HBD1 levels were linked to inflammatory cytokines and increased in highly inflamed samples.

CONCLUSIONS

Current oral drug treatment seems to have no major effect on the expression of antimicrobial peptides. In contrast to HBD2 and LL37, ileal levels of HD5 and HD6 and colonic HBD1 level are independent of current inflammation. Innovative drugs should aim to strengthen protective innate immunity.

Clinical trial: cyclophosphamide pulse therapy - a promising therapeutic alternative in refractory Crohn's disease

BACKGROUND

In severe steroid-refractory Crohn's disease (CD), established therapies fail in a relevant proportion of patients. Recent pilot studies indicated the efficacy of cyclophosphamide pulse therapy in these patients.

AIM

To provide further and substantial evidence for the rationale to apply cyclophosphamide pulse therapy as therapeutic option in severe courses of CD.

METHODS

Fifteen patients with steroid-refractory (n = 13) or steroid-dependent (n = 2) CD received 2-6 (median 3) monthly pulses of 750 mg cyclophosphamide in an open-label fashion. Eleven patients were on concomitant immunosuppression (azathioprine/mercaptopurine n = 9; methotrexate n = 2).

RESULTS

Thirteen of 15 patients (87%) had a clinical response (CDAI decrease >100). Ten patients (67%) went into remission (CDAI <150) after 8 weeks. Steroid-free remission was achieved in eight patients (54%). Two patients (13%) failed to respond. Median CDAI decreased from 420 (245-550) to 100 (26-538) at week 8. Remission lasted 16 months (median, range 4-40). In three patients, arthritis, erythema nodosum and episcleritis completely resolved. Cyclophosphamide pulse therapy administration was well tolerated in all subjects.

CONCLUSIONS

Cyclophosphamide pulse therapy is safe and highly effective for induction and maintenance of remission in steroid-refractory/-dependent CD. There is a strong need for additional experience to improve the setting of the encouraging cyclophosphamide treatment in CD.

Probiotic E. coli treatment mediates antimicrobial human beta-defensin synthesis and fecal excretion in humans

Inducible epithelial human beta-defensins (hBD) play an important role in intestinal barrier function. In vitro studies showed that clinically effective probiotics induce antimicrobial hBD-2. Here, we aimed to assess the in vivo effect in healthy volunteers and also addressed how defensins affect probiotic survival. Symbioflor 2 containing one strain of several viable genotypes of Escherichia coli was administered to 23 healthy individuals. After 3 weeks, fecal hBD-2 peptide was increased in 78% (mean 3.7-fold; P<0.0001). Interestingly, the fecal hBD-2 peptide was still elevated 9 weeks after treatment (P=0.008). In vitro studies revealed that this effect was mediated by only one out of three tested E. coli genotypes and comparable to probiotic E. coli Nissle 1917 (10- to 15-fold). Functional assays showed that all tested bacteria were similarly killed by defensins allowing to speculate about a suicidal character of this effect. Defensin induction seems to be a common and important mechanism of probiotic treatment.

Probiotic lactobacilli and VSL#3 induce enterocyte beta-defensin 2

Recent evidence suggests that probiotic bacteria may stabilize gut barrier function via induction of anti-microbial peptides such as defensins. This study aimed to elucidate the induction mechanism of the human beta defensin-2 (hBD-2) gene by different probiotic lactobacillus strains. The expression of hBD-2 mRNA peaked at 6 h of incubation upon treatment of Caco-2 cells and increased with higher dosage of various probiotic bacteria. Deletion of nuclear factor (NF)-kappaB and activator protein-1 (AP-1) binding sites on the hBD-2 promoter resulted in a complete abrogation of promoter activation by probiotics. As revealed by the use of specific mitogen-activated protein kinase (MAPK) inhibitors the hBD-2 induction was dependent on the MAPK extracellular regulated kinase (ERK 1/2), p38 and c-Jun N-terminal kinase (JNK), although to varying degrees. Several Lactobacillus strains and VSL#3, a probiotic cocktail of four lactobacilli, three bifidum and one streptococcus species, induced the secretion of the hBD-2 peptide into the culture media as shown by enzyme-linked immunosorbent assay (ELISA). Thus, the present study suggests that lactobacilli and the VSL#3 bacterial mixture strengthen intestinal barrier functions through the up-regulation of hBD-2 via induction of proinflammatory pathways including NF-kappaB and AP-1 as well as MAPKs.

Tacrolimus--finally!

Tacrolimus appears to be at least comparable to ciclosporin in refractory ulcerative colitis in terms of tolerability and efficacy but the oral route of administration and reliability of drug levels are advantageous

[Chronic inflammatory bowel diseases (IBD): novel pathophysiological concepts and their clinical relevance]

Despite many years of intensive research the pathogenesis of inflammatory bowel diseases is still enigmatic. All efforts to identify the cause of Crohn's disease and ulcerative colitis in a dysregulation of specific immune mechanisms have failed. This review presents a novel pathogenetic concept, based on the expression of natural mucosal antibiotic peptides. These so called defensins are part of innate immunity and defend the mucosa as antimicrobial peptides against intraluminal potentially pathogenic and invasive bacteria. In contrast to ulcerative colitis, Crohn's disease is characterised by a diminished defensin expression. This defect may represent the molecular pathogenesis of this disease.

Enhanced human beta-defensin-2 (hBD-2) expression by corticosteroids is independent of NF-kappaB in colonic epithelial cells (CaCo2)

Beta-defensins are small cationic peptides with antimicrobial properties that contribute to innate host defense. Unlike human beta-defensin-1 (hBD-1), which is produced constitutively, human beta-defensin-2 (hBD-2) is expressed after adequate stimulation by cytokines and/or bacterial endotoxins in epithelial tissue and mononuclear phagocytes but may be deficient in patients with Crohn's disease. To further elucidate the role of the intestinal epithelium in antimicrobial host defense, gene regulation of hBD-2 and the interaction with NF-kappaB were analyzed in a cell culture model. Human colonic epithelial cells (CaCo2) were stimulated by pro-inflammatory cytokines (IL-1beta, TNF-alpha, IF-gamma) to induce hBD-2 mRNA transcription. Interactions with NF-kappaB were analyzed using specific inhibitors (sulfasalazine, gliotoxine, dexamethasone) at different concentrations. Defensin mRNA expression was quantified by competitive RT-PCR and antibacterial capacity of supernatants was determined by an antimicrobial assay. HBD-2 mRNA transcription and antimicrobial activity of CaCo2 cells were induced by stimulation with pro-inflammatory cytokines. Induction was not inhibited by sulfasalazine or gliotoxine, whereas dexamethasone further enhanced both gene transcription and antimicrobial capacity. The lack of inhibition of induced hBD-2 expression by specific NF-kappaB antagonists suggests an additional pathway of activation, independent of NF-kappaB. The induction of hBD-2 expression in cytokine-stimulated CaCo2 cells by corticosteroids indicates further immunomodulatory ability of steroid hormones not yet understood.

NOD2 (CARD15) mutations in Crohn's disease are associated with diminished mucosal alpha-defensin expression

BACKGROUND

Mutations in NOD2, a putative intracellular receptor for bacterial peptidoglycans, are associated with a subset of Crohn's disease but the molecular mechanism linking this protein with the disease pathogenesis remains unclear. Human alpha defensins (HD-5 and HD-6) are antibiotic effector molecules predominantly expressed in Paneth cells of the ileum. Paneth cells also express NOD2. To address the hypothesis that the function of NOD2 may affect expression of Paneth cell defensins, we compared their expression levels with respect to NOD2 mutations in Crohn's disease.

METHODS

Forty five Crohn's disease patients (24 with NOD2 mutations, 21 with wild-type NOD2) and 12 controls were studied. Real time reverse transcription-polymerase chain reaction was performed with mucosal mRNA for HD-5, HD-6, lysozyme, secretory phospholipase A2 (sPLA2), tumour necrosis factor alpha, interleukin 8, and human hypoxanthine phosphoribosyltransferase (housekeeping gene). Immunohistochemistry with anti-HD-5 and histological Paneth cell staining were performed in 10 patients with NOD2 mutations or wild-type genotypes.

RESULTS

Ileal expression of HD-5 and HD-6, but not sPLA2 or lysozyme, were diminished in affected ileum, and the decrease was significantly more pronounced in patients with NOD2 mutations. In the colon, HD-5, HD-6, and sPLA2 were increased during inflammation in wild-type but not in NOD2 mutated patients. In both the colon and ileum, proinflammatory cytokines and lysozyme were unaffected by NOD2 status. Immunohistochemistry identified Paneth cells as the sole source of HD-5.

CONCLUSION

As alpha defensins are important in the mucosal antibacterial barrier, their diminished expression may explain, in part, the bacterial induced mucosal inflammation and ileal involvement of Crohn's disease, especially in the case of NOD2 mutations.

[The role of defensins in the pathogenesis of chronic-inflammatory bowel disease]

Defensins are endogenous antimicrobial peptides with a broad activity spectrum. Even at micromolar concentrations gramnegative and grampositive bacteria, but also mycobacteria, as well as fungi (candida), viruses (herpes) and protozoa (giardia lamblia) are destroyed. As part of the innate immune system defensins are expressed by the intestinal epithelium and contribute to the maintenance of the mucosal barrier. This barrier appears to be defective in inflammatory bowel diseases since on one hand, the immune response is directed against the "normal" luminal bacterial flora and on the other hand, mucosal adherent and invasive bacteria have been observed in these diseases. A defective defensin expression may well explain these phenomena. Indeed, Crohn's disease of the terminal ileum, especially if associated with a NOD2 mutation, is characterised by a diminished alpha-defensin (human defensin 5 and 6) expression, and in inflamed Crohn's colitis, in contrast to ulcerative colitis, the beta-defensin (human beta-defensins 2 and 3) response is reduced. Through a deficient chemical mucosal barrier this defect could lead to increased bacterial invasion into the intestinal mucosa and might well explain an adequate inflammatory response. Although the final proof that this deficient defensin response leads to a reduced antibacterial activity of the intestinal mucosa is still lacking, the most plausible concept of pathogenesis of Crohn's disease is a defensin deficiency syndrome.

Thioguanine-nucleotides do not predict efficacy of tioguanine in Crohn's disease

BACKGROUND

6-Thioguanine-nucleotides seem to be the active metabolites of thiopurine therapy, and their monitoring has been considered a useful tool for optimizing response in inflammatory bowel diseases. Tioguanine (thioguanine) therapy results in much higher levels of 6-thioguanine-nucleotide levels when compared with azathioprine or mercaptopurine.

AIM

To elucidate the influence of 6-thioguanine-nucleotide and methylated 6-thioguanine-nucleotide levels under tioguanine on efficacy and toxicity in Crohn's disease.

METHODS

6-Thioguanine-nucleotide and methylated 6-tioguanine-nucleotide levels were measured regularly in 26 Crohn's disease patients treated with tioguanine. Nucleotide levels were related to efficacy and toxicity.

RESULTS

6-Thioguanine-nucleotide levels rose very high [median 1241 pmol/8 x 10(8) red blood cells (range 313-1853)]. Methylated 6-thioguanine-nucleotide levels were detected in all patients [491 pmol/8 x 10(8) red blood cells (154-1775)]. 6-Thioguanine-nucleotide and methylated 6-thioguanine-nucleotide concentrations correlated significantly (r = 0.7, P < 0.0001). Nucleotide levels from patients achieving remission (n = 14) did not differ significantly from non-remitters (n = 12) [6-thioguanine-nucleotide: 1077 (599-2160) vs. 1210 (534-4665); methylated 6-thioguanine-nucleotide: 510 (214-1222) vs. 421 (145-1284)]. One patient with intermediate thiopurine S-methyltransferase activity experienced bone marrow toxicity upon dose escalation parallel with excessively high thioguanine-nucleotide levels.

CONCLUSIONS

6-Thioguanine-nucleotide as well as methylated 6-thioguanine-nucleotide levels under tioguanine therapy were not related to efficacy. This suggests that monitoring of 6-thioguanine-nucleotide levels is not a useful tool to predict response to thiopurines.

Remission maintenance by tioguanine in chronic active Crohn's disease

BACKGROUND

Tioguanine may offer an alternative for immunosuppression in chronic active Crohn's disease. Recently, we have shown that tioguanine is effective in inducing rapid remission.

AIM

To evaluate the role of tioguanine in the maintenance of remission in chronic active Crohn's disease.

METHODS

A follow-up study was performed to investigate the long-term efficacy and safety of and tolerance to tioguanine in chronic active Crohn's disease. Sixteen patients who had successfully received 6-tioguanine for remission induction were enrolled. The reasons for immunosuppressive therapy were steroid dependence (n = 10), steroid refractoriness (n = 6) and intolerance (n = 6) or refractoriness (n = 1) to azathioprine. After remission induction therapy for 6 months, patients were treated for another 6 months with a daily dose of 20-40 mg tioguanine. Primary outcomes were remission (Crohn's disease activity index < 150) and complete steroid reduction in steroid-dependent patients at 12 months. Laboratory controls of white blood count and liver enzymes, as well as erythrocyte tioguanine nucleotide levels, were performed regularly.

RESULTS

After 12 months of treatment, 14 of 16 (88%) patients were in remission, and 12 of these were completely free of systemic steroids. Adverse events during maintenance therapy included photosensitivity (one patient), minor viral infections (one), headache (four) and mild alopecia (one). One patient developed elevated liver enzymes, splenomegaly and thrombocytopenia, indicative of nodular regenerative hyperplasia of the liver.

CONCLUSIONS

In responders to tioguanine, the drug appears to be very effective in maintaining remission of chronic active Crohn's disease. Unfortunately, long-term hepatotoxicity seems to be an unpredictable and potentially severe adverse drug reaction. Therefore, to date, tioguanine cannot be recommended for general use outside clinical trials.

Defensin pattern in chronic gastritis: HBD-2 is differentially expressed with respect to Helicobacter pylori status

BACKGROUND/AIMS

Recent reports have suggested that Helicobacter pylori infection induces the mucosal antibiotic peptide human beta defensin 2 (HBD-2). Therefore, the present study investigated mRNA and peptide expression of four different defensins in the upper gastrointestinal tract in patients with H pylori positive and negative chronic gastritis.

MATERIALS/METHODS

Biopsies from the oesophagus to the duodenum were taken during routine gastroscopy in 71 individuals. Total RNA was extracted and the reverse transcription polymerase chain reaction was performed with primers for human defensins 5 and 6 (HD-5/6) or HBD-1 and HBD-2. Paraffin wax embedded tissue from gastric resections was tested for HD-5, HBD-1, and HBD-2 by immunohistochemistry.

RESULTS

Helicobacter pylori colonisation was associated with an increased percentage of positive biopsies with respect to HBD-2 in the corpus (p < 0.05). Helicobacter pylori had no impact on the gastric expression of HD-5 and HBD-1, whereas HD-6 was increased in the fundus. The abundant expression of alpha defensins in the duodenum and beta defensins in the oesophagus served as a positive control in each individual. Immunohistochemical analysis confirmed the presence of the HD-5, HBD-1, and HBD-2 peptides in gastric resection specimens.

CONCLUSIONS

The recently described induction of HBD-2 upon H pylori infection was confirmed in a clinical setting of chronic gastritis. This phenomenon may be mediated by components of the pathogen itself or may occur secondary to immune events in chronic inflammation.

6-thioguanine--efficacy and safety in chronic active Crohn's disease

BACKGROUND

: Azathioprine and mercaptopurine are commonly used in chronic active Crohn's disease. They share the disadvantage of a delayed onset of action and potentially serious side-effects, and are metabolized to thioguanine nucleotides which are thought to be the active metabolites. The direct use of 6-thioguanine may offer a more rapid and safer alternative. We conducted an open prospective study to investigate the efficacy and safety of 6-thioguanine in chronic active Crohn's disease.

METHODS

: Thirty-seven patients with chronic active Crohn's disease and a Crohn's disease activity index of > 150 were enrolled in this study. Inclusion criteria were steroid dependence (n = 19), steroid refractoriness (n = 9) and/or intolerance (n = 16) or refractoriness (n = 6) to azathioprine. Patients were treated with 40 mg/day of 6-thioguanine for 24 weeks; a dose escalation to 80 mg was allowed at week 12. Remission was defined as a Crohn's disease activity index of < 150 associated with a decrease of > 70 points; response was defined as a decrease of > 70 points in the Crohn's disease activity index.

RESULTS

: In the intention-to-treat analysis, 13 of 37 patients achieved remission (35%). Twelve of these 13 patients achieved remission after 4 weeks. Fifty-seven per cent of patients (21/37) achieved a response. The mean Crohn's disease activity index decreased from 284 +/- 74 to 153 +/- 101. 6-Thioguanine was more effective in azathioprine-intolerant than in azathioprine-refractory patients. Twelve of 16 patients intolerant to azathioprine tolerated 6-thioguanine. Adverse events included phototoxicity, pancreatitis, headache, nausea, alopecia, arthralgia, minor infections and reversible elevation of transaminases. Six patients required discontinuation of medication, two because of leucopenia.

CONCLUSIONS

: In this patient group with chronic active Crohn's disease, 6-thioguanine appeared to be effective with acceptable short-term toxicity, but long-term controlled trials are clearly needed to further define its role.

6-thioguanine--efficacy and safety in chronic active Crohn's disease

BACKGROUND

: Azathioprine and mercaptopurine are commonly used in chronic active Crohn's disease. They share the disadvantage of a delayed onset of action and potentially serious side-effects, and are metabolized to thioguanine nucleotides which are thought to be the active metabolites. The direct use of 6-thioguanine may offer a more rapid and safer alternative. We conducted an open prospective study to investigate the efficacy and safety of 6-thioguanine in chronic active Crohn's disease.

METHODS

: Thirty-seven patients with chronic active Crohn's disease and a Crohn's disease activity index of > 150 were enrolled in this study. Inclusion criteria were steroid dependence (n = 19), steroid refractoriness (n = 9) and/or intolerance (n = 16) or refractoriness (n = 6) to azathioprine. Patients were treated with 40 mg/day of 6-thioguanine for 24 weeks; a dose escalation to 80 mg was allowed at week 12. Remission was defined as a Crohn's disease activity index of < 150 associated with a decrease of > 70 points; response was defined as a decrease of > 70 points in the Crohn's disease activity index.

RESULTS

: In the intention-to-treat analysis, 13 of 37 patients achieved remission (35%). Twelve of these 13 patients achieved remission after 4 weeks. Fifty-seven per cent of patients (21/37) achieved a response. The mean Crohn's disease activity index decreased from 284 +/- 74 to 153 +/- 101. 6-Thioguanine was more effective in azathioprine-intolerant than in azathioprine-refractory patients. Twelve of 16 patients intolerant to azathioprine tolerated 6-thioguanine. Adverse events included phototoxicity, pancreatitis, headache, nausea, alopecia, arthralgia, minor infections and reversible elevation of transaminases. Six patients required discontinuation of medication, two because of leucopenia.

CONCLUSIONS

: In this patient group with chronic active Crohn's disease, 6-thioguanine appeared to be effective with acceptable short-term toxicity, but long-term controlled trials are clearly needed to further define its role.

Innate immunity and colonic inflammation: enhanced expression of epithelial alpha-defensins

Human alpha-defensins contribute to local intestinal host defense as part of innate immunity and may be of major relevance in microbial infection and chronic inflammatory bowel disease. The objective was to investigate human defensin 5 and 6 (HD-5, HD-6) mRNA expression by RT-PCR from colonic biopsies and peptide expression by immunohistochemistry from colonic resections under basal and inflammatory conditions. Both alpha-defensins were induced by proinflammatory cytokines in cell culture. HD-5 mRNA expression was enhanced in both idiopathic and nonidiopathic inflammatory states of the large bowel [32% of control vs 73% of unspecific colitis, 69% of Crohn's disease (CD) and 73% of ulcerative colitis (UC)], whereas HD-6 was specifically related to CD and UC (14% in controls vs 20% in unspecific coltis, 49% in CD and 42% in UC). Immunohistochemistry confirmed the presence of HD-5 in colonic epithelium. Antimicrobial peptides in the colon may be of importance in maintaining the mucosal barrier and controlling microbial invasion in inflammatory bowel diseases.

Alterations in pulmonary function in inflammatory bowel disease are frequent and persist during remission

OBJECTIVES

Information on the occurrence and frequency of pulmonary involvement in patients with inflammatory bowel disease (IBD) is inconsistent. The aim of this prospective study was to determine the frequency and type of pulmonary dysfunction in patients with IBD.

METHODS

Sixty-six patients with IBD (35 with Crohn's disease [CD] and 31 with ulcerative colitis [UC]) and 30 control patients were investigated with respect to the following pulmonary function tests: forced expiratory volume in 1 s (FEV1), inspiratory vital capacity (IVC), Tiffeneau value (FEV1/IVC), and lung CO transfer capacity (D(LCO)). Disease activity in IBD patients was assessed by the CD activity index for CD and the Truelove index for UC, respectively. Smoking habits and medication were documented in every patient.

RESULTS

Fourteen of 36 CD patients (39%) and 14 of 31 UC patients (45%) but only one of the controls exhibited at least one pathological (<80% of predicted value) pulmonary function test. In both CD and UC lung function tests were significantly decreased in comparison to the control group. This could be shown for FEV1 (-14% of predicted value in CD and -17% in UC, p < 0.01), IVC (-10% in CD and -12% in UC, p < 0.05), and DLCO (-20% in CD and -31% in UC, p < 0.01) without significant differences between both disease entities. The impairment of pulmonary function tests was more pronounced in patients with active disease than in those with inactive disease (FEV1, 81.4% vs 93.4% predicted, p < 0.02; IVC, 84.4% vs 93.7%, p < 0.05; DLCO, 80.4% vs 95.8%, ns).

CONCLUSIONS

IBD patients show significantly decreased lung function tests in comparison to healthy controls. The impairment in active disease exceeded that during remission.

Limited heat-shock protein 72 induction in Caco-2 cells by L-glutamine

BACKGROUND/AIMS

L-glutamine (L-gln) is a conditionally essential amino acid which is consumed by certain tissues like the intestine in large amounts as energy source during critical illness. Apart from nutritive action, recent data suggest a link to heat-shock protein (hsp) induction. We investigated the effect of L-gln on hsp72 expression in the intestinal cell line Caco-2 under basal and heat-shock conditions and compared it with related amino acids.

METHODS

Total cellular protein was extracted and separated by SDS-PAGE. Immunoblots were performed with anti-hsp72 followed by chemiluminescence detection and densitometric scanning.

RESULTS

Following heat shock, hsp72 protein expression increased by 72 and 53% at 2 and 4 mmol/l L-gln, respectively, compared to heat shock alone (p < 0.05). Under basal conditions a limited increase occurred only at 8 mmol/l L-gln (p < 0.01). Levels remained unaffected when related amino acids including alanine, glutamate or glycine were supplemented under basal and heat-shock conditions. Similarly, the nonmetabolizable glutamine analogue DON or the toxic metabolite L-pyroglutamate did not induce hsp72.

CONCLUSION

We conclude that the glutamine-mediated effect may be specifically attributed to the metabolic action of L-gln.

Defensins -- innate immunity at the epithelial frontier

Physical barrier function was formerly believed to play the major role in mucosal protection against luminal bacteria. This view has now been challenged by the discovery of specialized molecules that possess antimicrobial activity. More than 100 peptides have been identified so far, and the number is still growing. These peptides are distributed widely and conserved throughout phylogeny. The epithelial expression of antimicrobial peptides is of particular interest as many pathogens adhere to epithelial surfaces and may eventually invade the host. This rapidly acting defence system of innate immunity is already engaged before adoptive immune interactions take place. These antimicrobial peptides consist of constitutive and inducible forms, potentiating this barrier function in terms of an inflammatory response. One important subgroup of antimicrobial peptides is the family of defensins, which are classified as alpha (alpha-) and beta (beta-) defensins. Eight different peptides with varying antimicrobial properties have been identified. They are distributed widely in humans, and organ-specific expression patterns have been observed. Homologous peptides have been found in other mammals, vertebrates, invertebrates, insects and plants. The identification of alpha-defensins and their murine counterparts, cryptdins, in the small intestine prompted intensive research into epithelial antimicrobial defence.

Minimal renal dysfunction in inflammatory bowel disease is related to disease activity but not to 5-ASA use

BACKGROUND

Conflicting data exist about proteinuria in inflammatory bowel diseases. It is still unclear whether the occurrence of proteinuria in inflammatory bowel disease patients is an extra-intestinal manifestation of disease or the result of adverse effects to medication, especially to aminosalicylates (ASA).

METHODS

A total of 95 patients (51 with Crohn's disease and 44 with ulcerative colitis) were enrolled in the study. Disease activity was assessed by Crohn's Disease Activity Index (CDAI) or the Truelove index, respectively. Urine was collected over 24 h and protein excretion of specific marker proteins for tubular (alpha 1-microglobulin-alpha 1-MG) and glomerular (albumin-Alb, Immunoglobulin G-IgG) dysfunction was measured using a highly sensitive immunoluminometric assay.

RESULTS

Out of 51 Crohn's disease patients, 20 showed elevated urinary alpha 1-MG. The amount of alpha 1-MGuria was strongly correlated to the CDAI (r=0.6, P < 0.001). Only four Crohn's disease patients showed slightly elevated values for glomerular proteins in urine. Similar results were obtained for ulcerative colitis: whereas only two ulcerative colitis patients showed albuminuria, tubular proteinuria was detected in 28 out of 44 ulcerative colitis patients. Proteinuria was strongly dependent on disease activity (P < 0.01) but was not related to ASA treatment.

CONCLUSIONS

Proteinuria of tubular marker proteins occurs in the majority of inflammatory bowel disease patients and is related to disease activity rather than to ASA treatment. Tubular proteinuria seems to reflect a renal extra-intestinal manifestation of inflammatory bowel disease and may serve as a new relevant marker of disease activity.

[Sweet syndrome and erythema nodosum in ulcerative colitis, refractory to steroids: successful treatment with tacrolimus]

BACKGROUND

Inflammatory bowel disease is accompanied by cutaneous manifestations in about 10% of cases. Erythema nodosum and pyoderma gangraenosum are most frequently observed, which often subside on treatment of the underlying disease.

CASE REPORT

A 30-year-old male with a history of long-standing ulcerative colitis experienced an acute attack despite treatment with azathioprine. Further he noticed dull red, elevated and tender maculae on the forelegs. A disseminated and papulosquamous exanthema arose on the back of the trunk and the upper extremities without pruritus. Well-being was compromised and blood sampling revealed an inflammatory response. High-dose steroids with antibiotics were without benefit until they were combined with tacrolimus, an immunosuppressive agent acting similar to ciclosporin. Remission occurred rapidly and the skin lesions resolved. Six months later the patient is currently still in remission and developed no signs of recurrent exanthema.

CONCLUSION

The cutaneous lesions are thought to be related to ulcerative colitis and were classified as erythema nodosum and Sweet syndrome. This is the first report on the successful use of tacrolimus in steroid-refractory ulcerative colitis with extraintestinal cutaneous involvement.

Chronic hepatitis C, common variable immunodeficiency and autoimmune hemolytic anemia. Coincidence by chance or common etiology?

A case of chronic viral hepatitis is presented which is accompanied by an acquired immunodeficiency from the very beginning. Further problems arise by onset of an autoimmune hemolytic anemia. This is the first report on an association of chronic hepatitis C with acquired immunodeficiency and autoimmune hemolytic anemia. We assume in accordance with the patient's history that both have occurred as complications secondary to HCV infection. This adds another facet to the list of autoimmune phenomena during hepatitis C infection probably by induction of self-reactive B-cell clones.

Mycophenolate mofetil: lack of efficacy in chronic active inflammatory bowel disease

BACKGROUND

Mycophenolate mofetil (MMF) is a new immunosuppressant with pharmacodynamic properties comparable to azathioprine. Recent reports found MMF to be effective in inflammatory bowel disease (IBD).

METHODS

An open-label prospective and uncontrolled multicentre 6 month trial of MMF in combination with steroids was conducted in 24 chronic active IBD patients. A daily steroid demand of >/= 10 mg prednisone in the preceding 2 months and a Crohn's disease activity index (CDAI) > 150, or moderate to severe activity according to Truelove, served as criteria for chronic activity. The treatment consisted of a steroid pulse and tapering protocol in combination with MMF 2 g/day. A prednisone dose of 5 mg/day was maintained during months 4-6. The primary end-point was induction and maintenance of remission.

RESULTS

Only 10 of 24 patients had achieved remission after 3 months. All but one Crohn's disease patient had relapsed by the end of the study at 6 months. Depression and migraine necessitated drug withdrawal in two patients.

CONCLUSION

In conclusion, MMF 2 g/day was unable to induce and maintain remission for a period of 6 months in 23 of 24 chronic active IBD patients. Further controlled investigations are required in view of recent conflicting reports.

Mesenteric blood flow is related to disease activity and risk of relapse in ulcerative colitis: a prospective follow up study

BACKGROUND

The diagnostic significance of increased splanchnic blood flow in ulcerative colitis is unclear. This prospective study was therefore undertaken to define the role of Doppler sonography in the assessment of disease activity and in the prediction of early relapse.

SUBJECTS/METHODS

Splanchnic flowmetry was performed in 76 patients with ulcerative colitis (47 with active disease and 29 in remission), six with infectious colitis, and 13 healthy controls during fasting and 30 minutes after ingestion of a standardised meal. Twenty seven of the patients with ulcerative colitis and all patients with infectious colitis were investigated during the active state as well as in clinical remission and followed up for six months. Flow velocity and pulsatility index (PI) of the superior (SMA) and inferior (IMA) mesenteric arteries and the portal vein were related to clinical (Truelove index), laboratory (C-reactive protein), and endoscopic (Sutherland index) parameters of disease activity.

RESULTS

The mean flow velocity of the IMA correlated closest with clinical activity (Truelove, r = 0.41, p<0.005), the PI with C-reactive protein (r = 0.30, p<0.05), and endoscopic activity (r = 0.45, p<0.001). All patients in remission after six months (14/14) or with infectious colitis (6/6) showed an increase in PI of the IMA compared with the initial measurement during active disease (mean increase for ulcerative colitis +36% and for infectious colitis +77%). In contrast, most patients with later relapse or surgery (11/13) had decreased PI during initial remission (mean decrease -12%). The positive predictive value of this index for maintenance of remission was 0.77. Flow variables of the SMA and portal vein displayed weaker correlations.

CONCLUSIONS

Flow measurements in the IMA are closely related to clinical and endoscopic disease activity in patients with ulcerative colitis. Repeated measurement of the PI allows estimation of the risk of recurrence.

Enhanced intestinal expression of heat shock protein 70 in patients with inflammatory bowel diseases

Heat shock protein (Hsp) 70 is stress-inducible and exhibits both protective and antigenic properties. This study investigated the mucosal expression of the constitutive (Hsp70c) and inducible form (Hsp70i) as well as antibodies against human Hsp70 in inflammatory bowel disease and controls. Biopsies were assessed by immunoblot and immunofluorescence, resection specimens by immunohistochemistry, and mucosal antibody content by isoelectric focusing. Compared to controls, expression of Hsp70 was enhanced in ulcerative colitis (P<0.05), less so in Crohn's disease and infectious colitis. Strong epithelial staining was found for Hsp70c and Hsp70i in both diseases. Mucosal and submucosal mononuclear cells showed enhanced Hsp70c expression in Crohn's disease and to a lesser degree in ulcerative colitis. Antibodies of isotypes A or M were detected in nearly all patients and controls. The different pattern of Hsp70 expression in Crohn's disease compared to ulcerative colitis points to a distinct protective and immunological function, whereas a role in autoimmunity seems unlikely.

Steroid-unresponsive acute attacks of inflammatory bowel disease: immunomodulation by tacrolimus (FK506)

OBJECTIVE

Steroid treatment failure in acute Crohn's disease and ulcerative colitis frequently necessitates surgical intervention. Several alternative therapeutic strategies have been raised. The most promising so far has been intravenous cyclosporine, but the results in the long term have been discouraging. We assessed the efficacy and safety of the new macrolide immunomodulator tacrolimus as an alternative to cyclosporine A.

METHODS

Eleven patients with steroid-refractory disease (six ulcerative colitis, two indeterminate colitis, two Crohn's disease, one pouchitis) and severe activity according to the Truelove and Witts criteria or Crohn's disease activity index > 150, respectively, were eligible for the study. All patients were treated with intravenous tacrolimus for 7-10 days followed by oral treatment over a median period of 7 months (range 0.25-16). Azathioprine and mesalamine were given concomitantly. Steroids were tapered according to clinical activity.

RESULTS

Seven of 11 patients achieved remission rapidly, whereas a modest improvement was noted in two. Only two patients required an early and one a delayed colectomy. Moreover, a rectovaginal fistula closure in a case of Crohn's disease and an improvement of pouchitis was observed. A tapering to low dose steroids was possible during oral tacrolimus therapy in all nine responders and remission was maintained in five of them (mean follow-up 9.2 months). The drug was well tolerated and side effects were managed conservatively.

CONCLUSION

Tacrolimus induced rapid remission in steroid resistant inflammatory bowel disease in the majority of cases. It appears to be an effective treatment modality that may be superior to cyclosporine with respect to maintenance of remission.

Intestinal expression of human heat shock protein 90 in patients with Crohn's disease and ulcerative colitis

Heat shock proteins are induced by several stress factors and are potential antigens in autoimmune disorders. Expression of heat shock protein 90 (HSP 90) was investigated in patients with inflammatory bowel disease and normal controls. We combined western blot analysis with laser densitometry for quantitation. Localization of HSP 90 was investigated by immunohistochemistry. Western blots showed a significant mucosal expression of HSP 90, which was comparable in patients and controls. There was also no difference between normal and inflamed mucosa in inflammatory bowel disease. In immunohistochemical staining studies, HSP 90 was detected in epithelial cells, mononuclear cells, giant cells, nerve cells, and endothelial cells of small vessels. There was no difference in the intensity of staining or localization in patients with inflammatory bowel disease compared to controls. These findings render a potential protective or immunogenic function of HSP 90 in inflammatory bowel disease unlikely.

Crohn's disease and sarcoidosis: systemic granulomatosis?

We report an unusual case of severe Crohn's disease with involvement of the lung. In 1993 at age 21 a male patient experienced a Helicobacter-negative duodenitis. A routine chest radiograph revealed spotted opacities in the right upper lobe without discomfort and normal pulmonary function except for a reduced diffusion capacity. Bronchoalveolar lavage showed mild lymphocytosis and biopsies from the macroscopically normal bronchi displayed non-caseating granulomas. In 1995 he had symptoms of peptic ulcer disease with a gastric outlet stenosis. He underwent Billroth I resection with only temporary improvement. Three months later the symptoms had recurred and a stenosing inflammatory process of the duodenum was seen on endoscopy suggesting Crohn's disease. A chest radiograph demonstrated infiltrations in parts of the left lung and bronchoalveolar lavage again revealed alveolar lymphocytosis (CD4/CD8 ratio 3.1). Both the gastrointestinal and pulmonary affections responded to corticosteroids but the duodenal stricture had to be resected. The association of Crohn's disease and pulmonary disorders is discussed.

Reduced cholesterol esterification in CaCo-2 cells by indirect action of pravastatin

In microsomal preparations of CaCo-2 cells pravastatin decreased cholesterol esterifying activity at 25 micrograms/ml to 82.5% and at 800 micrograms/ml to 56.2% of controls. Pravastatin reduced cholesteryl ester formation dose-dependently also in viable CaCo-2 cells. However, the maximal inhibition was by 90.4% at pravastatin concentration of 25 micrograms/ml, half maximal inhibition occurred between concentrations of 5 and 10 micrograms/ml. Addition of mevalonolactone, which serves as endogenous source of cholesterol, antagonized this effect. At 10 mM mevalonolactone (MVL) even doses up to 200 micrograms/ml of pravastatin were ineffective. On the other hand, pravastatin suppressed cholesteryl ester formation when acyl-CoA cholesterol acyltransferase (ACAT) (E.C. 2.3.1.26) activity was stimulated by addition of exogenous liposomal or Low Density Lipoprotein (LDL)-derived cholesterol. This inhibition was refractory to increasing amounts of exogenous cholesterol up to 400 micrograms/ml. Therefore we conclude that only excessive doses of pravastatin suppress ACAT activity directly. In viable cells the observed inhibition of cholesteryl ester formation is due to the block in de novo synthesis of cholesterol, causing a lack of substrate for ACAT and of non-sterol products of mevalonic acid. Furthermore pravastatin interferes with the esterification and/or intracellular transport only of exogenous cholesterol, confirming former results of a compartmentalized cholesterol metabolism in the enterocyte.

Mevinolin, a competitive inhibitor of hydroxymethylglutaryl coenzyme A reductase, suppresses enterocyte esterification of exogenous but not endogenous cholesterol

Mevinolin (lovastatin), a competitive inhibitor of hydroxymethylglutaryl-coenzyme A reductase, directly inhibited acyl-CoA cholesteryl acyltransferase in rabbit intestinal microsomes at a dose of 20 micrograms/ml or more. Lineweaver-Burk analysis showed a competitive type of inhibition with respect to oleoyl-CoA. In cultured intestinal Caco-2 cells, mevinolin reduced [14C]oleate incorporation into cholesteryl-esters by 86% of controls at doses as low as 0.1 micrograms/ml. However, in cells whose activity of acyl-CoA cholesteryl acyltransferase was stimulated 7-fold by 10 mM mevalonolactone, a significant inhibitory effect on cholesteryl-ester formation could not be detected, even at 40 micrograms/ml of mevinolin. In contrast, cells supplied with liposomal cholesterol or cholesterol derived from low-density lipoproteins showed a marked reduction of cholesteryl-ester formation in the presence of 10 or 0.1 micrograms/ml of mevinolin, respectively. It is concluded that the observed suppressive effects of mevinolin on cholesterol esterification in cultured Caco-2 cells are indirect and possibly caused by changes in the acyl-CoA cholesteryl acyltransferase substrate pool or intracellular cholesterol transport.

Regulation of cholesterol metabolism and low-density lipoprotein binding in human intestinal Caco-2 cells

In the present paper, the regulation of 3-hydroxy-3-methylglutarylcoenzyme A (HMG-CoA) reductase, acylcoenzyme A cholesterol acyltransferase (ACAT) and low-density lipoprotein (LDL) binding was studied in the human colon cancer carcinoma cell line Caco-2. LDL down-regulated HMG-CoA reductase activity in a dose-dependent fashion to a minimum of 28% of control at 200 micrograms/ml and LDL binding to 52% of control. The activity of ACAT was stimulated by LDL. High-density lipoprotein 3 (HDL3) increased HMG-CoA reductase activity, whereas cholesteryl ester formation was slightly decreased. Inhibition of the endogenous cholesterol biosynthesis by mevinolin increased both LDL binding and activity of HMG-CoA reductase. This effect was reversed by the addition of mevalonolactone but not by LDL. It is concluded that regulation of HMG-CoA reductase and LDL binding is subject to the availability of non-sterol products of mevalonic acid and of exogenous cholesterol. ACAT is regulated mainly by the level of its substrate cholesterol.