Christoph Gasche

ANEMIA IN CROHN'S DISEASE : IMPORTANCE OF INADEQUATE ERYTHROPOIETIN PRODUCTION AND IRON DEFICIENCY

Intestinal blood loss as well as chronic inflammation are regarded as the most important mechanisms in the pathogenesis of anemia in Crohns disease. In addition, cytokines such as interleukin-6 can suppress erythropoietin production. This study was performed to investigate the importance of iron status, inflammatory activity, and endogenous erythropoietin concentrations for the development of anemia in Crohns disease. In 49 consecutive patients with Crohns disease, hemoglobin, inflammatory activity (Crohns disease activity index, C-reactive protein, α1-acid glycoprotein), iron status (serum iron, transferrin, transferrin saturation, ferritin), and serum erythropoietin levels were studied. Anemic (Hb<12.0 g/dl;N=16) vs nonanemic patients (Hb≥12 g/dl;N=33) showed reduced iron compartments (eg, ferritin 28.7±12.9 µg/liter vs 63.2±15.0 µg/liter, transferrin saturation 6.2±1.4% vs 11.5±1.3%,P<0.01) but no differences in inflammatory activity. An inverse correlation between erythropoietin and hemoglobin concentrations was found (r=-0.62;P<0.001), but the increase in erythropoietin levels was inadequate to the degree of anemia. There was no correlation between erythropoietin and interleukin-6 serum levels. Four of five anemic patients with hemoglobin below 10.5 g/dl and erythropoietin levels within the normal range were treated with parenteral iron (200 mg iron saccharate in 250 ml NaCl, weekly, intravenously). Two of them additionally received recombinant human erythropoietin (150 units/kg, 3× weekly, subcutaneously). After five weeks all patients had a marked increase in hemoglobin. However, the mean increase in erythropoietin-treated patients was 5.0 g/dl compared to 2.0 g/dl in the patients with iron therapy only. No side effects were seen. Our data demonstrate that inadequate erythropoietin production and iron deficiency are pathogenetic factors of anemia in Crohns disease. The therapeutic management using recombinant human erythropoietin and parenteral iron is reasonable and effective.

IL-10 secretion and sensitivity in normal human intestine and inflammatory bowel disease.

Interleukin-10 (IL-10) deficiency in gene knockout mice causes chronic enterocolitis. We hypothesized that inflammation in human inflammatory bowel disease might result from innate alterations in the IL-10 pathway. Serum, supernatants, and mRNA of peripheral blood mononuclear cells (PBMC) and lamina propria mononuclear cells (LPMC) derived from inflamed (LPMC-i) and noninflamed colonic mucosa (LPMC-ni) were collected from patients with Crohns colitis, ulcerative colitis, and controls. IL-10 protein concentrations and IL-10 mRNA were examined in response to PMA/CD3 or PHA stimulation. The response to rhIL-10 was assessed by inhibition of tumor necrosis factor-alpha (TNF-α), IL-6, and interferon-gamma (IFN-γ) production. Serum IL-10 levels of inflammatory bowel disease (IBD) patients were within the normal range. IL-10 concentrations in supernatants from LPMC-i were significantly lower than from LPMC-ni or PBMC. No difference was seen between samples from ulcerative colitis and Crohns disease. IL-10 mRNA was detected in 0/4 LPMC-i samples compared to 1/6 LPMC-ni and 6/6 PBMC. RhIL-10 inhibited TNF-α, IL-6, and IFN-γ synthesis in PBMC. This effect was strongly diminished in LPMC. Disease-specific alterations were not detected. Our data suggest that LPMC derived from inflamed colonic mucosa have a reduced ability to produce and to respond to rhIL-10. A disease-specific alteration in the IL-10 pathway, however, was not found.

Significant association of strictures and internal fistula formation in Crohn's disease.

Abstract Intestinal inflammation in Crohn’s disease (CD) may be complicated by the occurrence of strictures and fistulae. The pathogenesis of fistula formation is unknown. We therefore wanted to determine whether mechanical factors might contribute to the development of fistulae. Furthermore, we tried to define the path of internal fistulae through the muscular layer. For this purpose, surgical resection specimens from 42 consecutive patients with CD were prospectively studied. In gross examination the whole bowel was cut into circumferential cross sections 0.3 cm thick. Abnormal areas were histologically examined. Strictures were found in 38 patients (90.5%), and fistulae were observed in 27 (64.3%) patients. In 11 (40.7%) specimens fistulae were found within a stricture, in 15 (55.6%) at the proximal end, and in 1 (3.7%) no stricture was found. In 7 (25.9%) cases with fistulae, herniated mucosa was found within the muscularis propria or the subserosa. In 7 (25.9%) cases a blood vessel was identified near a fistula traversing the muscularis propria. From these findings we conclude that that mechanical factors may contribute to fistula formation. This is further supported by the fact that fistulae appear to traverse the muscular layer along piercing vessels.

Novel Variants of the IL-10 Receptor 1 Affect Inhibition of Monocyte TNF-α Production

IL-10-deficient mice exhibit spontaneous enterocolitis and other symptoms akin to Crohn’s disease, indicating that IL-10 might regulate normal physiology in the gut. However, clinical trials with IL-10 in Crohn’s disease were disappointing, although some patients showed healing of intestinal mucosa. This study searched for genetic polymorphisms within the IL-10 pathway. We decided to screen for mutations of the IL-10R1 cDNA in healthy volunteers and Crohn’s disease patients and identified two novel variants: a serine 138-to-glycine (S138G) and a glycine 330-to-arginine (G330R) substitution. The allelic frequency in a European cohort was relatively high (16% for the S138G and 33% for the G330R), and S138G was in strong linkage disequilibrium with G330R. A similar allele frequency was found in a group of Crohn’s patients. In IL-10R1 G330R-expressing monocytes, the inhibitory effect of IL-10 on TNF-α production was diminished, indicating that this variant may be a loss-of-function allele. No such difference was observed between haplotypes 4 (G330R only) and 7 (S138G and G330R). In addition, these IL-10R1 variants had no influence on the IL-10R1 expression density. Structural analysis of the S138G variant revealed that the substitution of S138G may interfere with binding of IL-10 to IL-10R1.

Prospective evaluation of interferon-α in treatment of chronic active Crohn's disease

Several case reports suggested good effects of interferon-α in patients with Crohns disease. In addition, a decreased production of interferon-α in Crohns disease has been shownin vitro. Treatment with interferon-α may activate intestinal natural killer cells and down-regulate the overproduction of inflammatory cytokines like interleukin-6 in Crohns disease. To evaluate the clinical efficacy of interferon-α, we treated 12 patients with a chronic active course of Crohns disease with recombinant human interferon-α prospectively for 24 weeks. Prednisolone was continuously tapered and discontinued at week 12. The end point of the study was the prevention of worsening of clinical symptoms defined with the Crohns disease activity index and was monitored by acute-phase proteins, interleukin-6 serum concentrations, and endoscopy. The biochemical activity of interferon-α was measured by 2′,5′-oligo adenylate serum levels. The end point of the study was reached in four patients (33%). In these patients the final Crohns disease activity index was above 150, which means that they did not achieve clinical remission. All other patients (66%) did not respond to interferon-α and had to be withdrawn prematurely. Interferon-α did not show any beneficial effect on interleukin-6 or acute-phase protein concentrations and on endoscopic activity. The 2′,5′-oligo adenylate levels continuously increased during interferon therapy. Considerable side effects were noted. These results fail to demonstrate a therapeutic role of interferon-α in chronic active Crohns disease.

A novel variant of lysosomal acid lipase in cholesteryl ester storage disease associated with mild phenotype and improvement on lovastatin.

Cholesterol ester storage disease (CESD) is a rare congenital disorder of lipid metabolism, with mutation of the lysosomal acid lipase gene, causing chronic liver disease, usually before adolescence. We here describe three adult siblings with CESD diagnosed by light microscopic demonstration of excessive lysosomal storage of lipids with accumulation of foamy cells in liver biopsies and by a decrease in acid lipase activity (2-3% of controls). One patient (male, 46a) had extensive liver fibrosis, another (female, 58a) had cirrhosis of the liver. The third patient had died from variceal haemorrhage (female, 56a). Using sequence analysis of RT-PCR products of LAL mRNA, the patients were identified as compound heterozygotes for a G-->A substitution at position -1 of the exon 8 splice donor site and a point mutation at the second allele, resulting in a His108-->Pro shift. In two patients, therapy with lovastatin was initiated, which led to normalisation of serum cholesterol and triglyceride levels. After 12 months, liver biopsy demonstrated a significant decrease in vacuolisation of hepatocytes, with fewer and smaller droplets. Semi-automated computer-assisted image analysis of electron microscopic sections demonstrated a decrease in the hepatocellular lysosomal area from 20.5+/-7.1% to 11.7+/-6.5% (p<0.05) and 41.7+/-5.1% to 33.4+/-4.4% (p<0.01). We conclude that in two siblings with a novel LAL variant and mild phenotype of CESD, lovastatin decreased both serum lipid concentrations and hepatocellular lysosomal content.

Different missense mutations in histidine-108 of lysosomal acid lipase cause cholesteryl ester storage disease in unrelated compound heterozygous and hemizygous individuals

Cholesteryl ester storage disease (CESD) and Wolman disease (WD) are both autosomal recessive disorders associated with reduced activity of lysosomal acid lipase (LAL), that leads to the tissue accumulation of cholesteryl esters in endosomes and lysosomes. WD is caused by genetic defects of LAL that leave no residual enzymatic activity, while in CESD patients a residual LAL activity can be identified. We have analyzed the LAL cDNA in three CESD patients from two nonrelated families and identified the mutations responsible for the disease. The associated genetic defects characterized revealed compound heterozygosity for a splice defect leading to skipping of exon 8, due to a G→A transition at position –1 of the exon 8 splice donor site, and a point mutation leading to a His108Pro change (CAT→CCT) in two patients (siblings) with mild CESD phenotype. A further CESD patient was hemizygous for a His108→Arg missense mutation (CAT→CGT) in combination with a partial deletion of the LAL gene and was affected more severely. Expression of the LAL enzymes with the His108→Pro and His108→Arg mutation in insect cells revealed residual enzymatic activities of 4.6% versus 2.7%, respectively, compared with controls. Therefore, His108 seems to play a crucial role in folding or catalytic activity of the lysosomal acid lipase. This is the first description of two different, naturally occurring mutations involving the same amino acid residue in the lysosomal acid lipase in unrelated CESD patients. Moreover, our results demonstrate that the variable manifestation of CESD can be explained by mutation‐dependent, variable inactivation of the LAL enzyme. Hum Mutat 12:44–51, 1998.

Altered mononuclear phagocyte differentiation associated with genetic defects of the lysosomal acid lipase

Multiparameter flow cytometry reveals a complex heterogeneity of mononuclear phagocyte differentiation within the peripheral blood compartment. In this study, the relation of abnormal cellular lipid metabolism to the phenotype of peripheral blood mononuclear phagocytes, which finally may be related to atherogenesis, was analyzed using recently characterized autosomal recessive defects of lysosomal acid lipase (LAL) expression as model system. The reduction of LAL activity in nine heterozygote, disease free carriers of mutations from two cholesteryl ester storage disease (CESD) pedigrees and the family of a patient with Wolman disease was associated with an increased fraction of monocytes which expressed CD56 (N-CAM) (4.1 +/- 2.7% of monocytes, compared to 2.2 +/- 0.5% in ten controls, P < 0.05), an antigen characteristic of immature myeloid cells, suggesting an increased turnover of monocytes. Furthermore, a trend was observed towards an enhanced blood pool of more mature mononuclear phagocytes which show decreased expression of the 55 kD lipopolysaccharide receptor (CD14) together with either expression of the Fc-gamma-receptor III (CD16) or a high expression of CD33. A similar phenotype of peripheral mononuclear phagocytes was observed in the two CESD patients analyzed. In conclusion, our data suggest that these monogenetic defects of lysosomal lipoprotein metabolism are associated with complex alterations of mononuclear phagocyte differentiation and extravasation.

Genotype-phenotype correlations: how many disorders constitute inflammatory bowel disease?

Various chromosomal loci transfer susceptibility to the development of Crohns disease and/or ulcerative colitis. The disease-causing gene on one of these loci (IBD1) has been identified as CARD15/NOD2 and certain loss-of-function mutations were linked to the development of Crohns disease. The recent data from association studies of CARD15/NOD2 mutations with certain phenotypes of Crohns disease are reviewed. These mutations link to early onset ileal and fibrostenotic disease corresponding to the A1/L1 or L3/B2 subgroup of the Vienna classification. The present data on variations in HLA or cytokine genes suggest that these genes are disease modifying rather than disease predisposing. Certainly, inflammatory bowel diseases consist of more than two genotypes and phenotypes. At this stage, predictions on the number of disease causing genes, mutations or environmental factors are impossible.

Influence of topically and systemically active steroids on circulating leukocytes in Crohn’s disease

Objective:Budesonide, although only topically active, is effective in the treatment of Crohns disease. This study was performed to compare the clinical efficacies of budesonide and prednisolone in relation to the activation status of circulating leukocytes.Methods:Twenty-four patients with active Crohns disease were randomized to treatment with either budesonide or 6-methylprednisolone. Clinical response was monitored by the Crohns disease activity index, C-reactive protein, and orosomucoid. Expression of CD25 and CD71 on T cells and CD64 on neutrophils was determined by flow cytometry. The release of TNF-α and IL-1β by peripheral blood mononuclear cells was measured by ELISA.Results:After 2 wk of treatment a clinical response was observed in both groups, but it was more accentuated in patients treated with prednisolone. At baseline an upregulation of CD71 and CD64, but not CD25, was found in active patients. Prednisolone significantly decreased the expression of CD64 and the release of TNF-α and IL-1β, but did not alter the expression of CD25 and CD71. Budesonide treatment failed to exert any effect on circulating leukocytes.Conclusions:The inability of budesonide to downregulate activated circulating leukocytes may contribute to the somewhat lower clinical efficacy of this topical steroid in the treatment of active Crohns disease.