A trial of mercaptopurine is a safe strategy in patients with inflammatory bowel disease intolerant to azathioprine: an observational study, systematic review and meta-analysis

BACKGROUND

Thiopurines maintain remission and modify disease course in inflammatory bowel disease. Use is limited by intolerance and subsequent drug withdrawal in approximately 17% of patients treated with azathioprine. Previous case series have addressed the success rates of re-treatment with mercaptopurine in these individuals.

AIMS

To determine the rate of tolerance when trialling mercaptopurine in azathioprine-intolerant patients and the factors predictive of success, and to perform a systematic review and meta-analysis of these data with other published data sets.

METHODS

A retrospective observational study of 149 patients with IBD (82 with Crohn's disease and 67 with ulcerative colitis) previously intolerant of azathioprine subsequently treated with mercaptopurine was performed. A meta-analysis was undertaken of all published studies of mercaptopurine use in azathioprine-intolerant patients (455 patients in 11 included studies).

RESULTS

Mercaptopurine was tolerated by 58% of azathioprine-intolerant patients in the Edinburgh cohort. In the meta-analysis, 68% tolerated mercaptopurine. A higher proportion of those in the meta-analysis with GI toxicity (62%) or hepatotoxicity (81%) were able to tolerate mercaptopurine than those with flu-like illness (36%). Among those patients who ceased mercaptopurine for further adverse effects, 59% experienced the same adverse effect as they had with azathioprine.

CONCLUSIONS

This meta-analysis shows that switching to mercaptopurine is a safe therapeutic strategy for over two-thirds of azathioprine-intolerant patients and may help optimise immunomodulatory therapy in inflammatory bowel disease. A trial of mercaptopurine should be attempted in IBD patients (except those with acute pancreatitis or bone marrow aplasia) before considering thiopurine intolerance.

Regional variation in gene expression in the healthy colon is dysregulated in ulcerative colitis

OBJECTIVE

To investigate differential intestinal gene expression in patients with ulcerative colitis and in controls.

DESIGN

Genome-wide expression study (41,058 expression sequence tags, 215 biopsies).

SETTING

Western General Hospital, Edinburgh, UK, and Genentech, San Francisco, USA.

PATIENTS

67 patients with ulcerative colitis and 31 control subjects (23 normal subjects and 8 patients with inflamed non-inflammatory bowel disease biopsies).

INTERVENTIONS

Paired endoscopic biopsies were taken from 5 specific anatomical locations for RNA extraction and histology. The Agilent microarray platform was used and confirmation of results was undertaken by real time polymerase chain reaction and immunohistochemistry.

RESULTS

In healthy control biopsies, cluster analysis showed differences in gene expression between the right and left colon. (chi(2) = 25.1, p<0.0001). Developmental genes, homeobox protein A13 (HOXA13), (p = 2.3x10(-16)), HOXB13 (p<1x10(-45)), glioma-associated oncogene 1 (GLI1) (p = 4.0x10(-24)), and GLI3 (p = 2.1x10(-28)) primarily drove this separation. When all ulcerative colitis biopsies and control biopsies were compared, 143 sequences had a fold change of >1.5 in the ulcerative colitis biopsies (0.01>p>10(-45)) and 54 sequences had a fold change of <-1.5 (0.01>p>10(-20)). Differentially upregulated genes in ulcerative colitis included serum amyloid A1 (SAA1) (p<10(-45)) the alpha defensins 5 and 6 (DEFA5 and 6) (p = 0.00003 and p = 6.95x10(-7), respectively), matrix metalloproteinase 3 (MMP3) (p = 5.6x10(-10)) and MMP7 (p = 2.3x10(-7)). Increased DEFA5 and 6 expression was further characterised to Paneth cell metaplasia by immunohistochemistry and in situ hybridisation. Sub-analysis of the inflammatory bowel disease 2 (IBD2) and IBD5 loci, and the ATP-binding cassette (ABC) transporter genes revealed a number of differentially regulated genes in the ulcerative colitis biopsies.

CONCLUSIONS

Key findings are the expression gradient in the healthy adult colon and the involvement of novel gene families, as well as established candidate genes in the pathogenesis of ulcerative colitis.

Low body mass not vitamin D receptor polymorphisms predict osteoporosis in patients with inflammatory bowel disease

BACKGROUND

Osteoporosis is a recognized complication of inflammatory bowel disease (IBD). Aim To investigate the role of environmental factors and vitamin D receptor (VDR) variants on the prevalence of osteoporosis.

METHODS

DEXA scans and case note review were performed on 440 IBD patients from 1997 to 2006. All the IBD patients and 240 healthy controls were genotyped for VDR variants Taq-1 and Apa-1 using PCR-RFLP.

RESULTS

Osteoporosis and osteopenia rates were 15% and 18% for IBD, 16% and 18% for Crohn's disease (CD) and 13% and 19% for ulcerative colitis, respectively. On univariate analysis of the CD patients, low body mass index (BMI, <18.5) and smoking status (P = 0.008 and 0.005 respectively) were associated with osteoporosis and osteopenia. Low BMI was also associated with osteoporosis on multivariate analysis in CD (P = 0.021, OR 5.83, CI 1.31-25.94). No difference was observed between Taq-1 and Apa-1 VDR polymorphisms in IBD, CD, ulcerative colitis and healthy controls. However, CD males were more likely to carry the variant Taq-1 polymorphism than healthy controls males (P = 0.0018, OR 1.94, CI 1.28-2.92) and female CD patients (P = 0.0061, OR 1.60, CI 1.17-2.44).

CONCLUSIONS

In this well-phenotyped cohort of IBD patients, a relatively low prevalence of osteoporosis was observed. Low BMI was the only independent risk factor identified to be associated with osteoporosis.

Gender-stratified analysis of DLG5 R30Q in 4707 patients with Crohn disease and 4973 controls from 12 Caucasian cohorts

BACKGROUND

DLG5 p.R30Q has been reported to be associated with Crohn disease (CD), but this association has not been replicated in most studies. A recent analysis of gender-stratified data from two case-control studies and two population cohorts found an association of DLG5 30Q with increased risk of CD in men but not in women and found differences between 30Q population frequencies for males and females. Male-female differences in population allele frequencies and male-specific risk could explain the difficulty in replicating the association with CD.

METHODS

DLG5 R30Q genotype data were collected for patients with CD and controls from 11 studies that did not include gender-stratified allele counts in their published reports and tested for male-female frequency differences in controls and for case-control frequency differences in men and in women.

RESULTS

The data showed no male-female allele frequency differences in controls. An exact conditional test gave marginal evidence that 30Q is associated with decreased risk of CD in women (p = 0.049, OR = 0.87, 95% CI 0.77 to 1.00). There was also a trend towards reduced 30Q frequencies in male patients with CD compared with male controls, but this was not significant at the 0.05 level (p = 0.058, OR = 0.87, 95% CI 0.74 to 1.01). When data from this study were combined with previously published, gender-stratified data, the 30Q allele was found to be associated with decreased risk of CD in women (p = 0.010, OR = 0.86, 95% CI 0.76 to 0.97), but not in men.

CONCLUSION

DLG5 30Q is associated with a small reduction in risk of CD in women.

A retrospective analysis of the efficacy and safety of infliximab as rescue therapy in acute severe ulcerative colitis

BACKGROUND

Forty per cent of patients with acute severe ulcerative colitis will not respond to intravenous corticosteroids and require second-line medical therapy or colectomy. A recent controlled trial has suggested that infliximab may be effective as rescue therapy.

AIM

To assess the value of infliximab as rescue therapy for acute severe colitis in a retrospective cohort of ulcerative colitis patients in Scotland.

METHODS

All patients satisfied Truelove and Witts criteria on admission, failed to respond to intravenous corticosteroids and received infliximab (5 mg/kg) as rescue therapy. Response was defined as need for colectomy at hospital discharge and by 90 days.

RESULTS

A total of 39 patients (median age 31.7 years) were treated. 26/39 (66%) responded, avoiding colectomy during the acute admission, and were followed up for a median of 203 days (Interquartile range = 135.5-328.5). Hypoalbuminaemia was a consistent predictor of non-response on univariate and multivariate analysis. At day 3 of intravenous steroids, 9/18 (50.0%) with serum albumin <34 g/L had urgent colectomy vs. 1/13 (7.7%) >or=34 g/L (P = 0.02, OR = 12.0, C.I. 1.28-112.7). Two serious adverse events occurred - one death due to Pseudomonas pneumonia, and one post-operative fungal septicaemia.

CONCLUSIONS

Infliximab represents a moderately effective rescue therapy for patients with acute severe ulcerative colitis. Serious adverse events, including death, do occur and should be discussed with patients prior to therapy.

Analysis of the influence of OCTN1/2 variants within the IBD5 locus on disease susceptibility and growth indices in early onset inflammatory bowel disease

BACKGROUND AND AIMS

The OCTN1 (SLC22A4 1672C-->T) and OCTN2 (SLC22A5 -207G-->C) variants within the IBD5 locus have been associated with susceptibility to adult onset Crohn's disease (CD), but their contribution in children has not been examined.

METHODS

These OCTN1/2 variants and IBD5 marker single nucleotide polymorphisms (SNPs) (IGR2096a_1, IGR2198a_1, and IGR2230a_1) were examined in 299 Scottish children (200 with CD, 74 with ulcerative colitis (UC), and 25 with indeterminate colitis (IC)), together with 502 parents (for transmission disequilibrium testing) and 256 controls.

RESULTS

All SNPs were in strong linkage disequilibrium (D' >0.94). TDT analysis showed association of the OCTN1 variant with inflammatory bowel disease (IBD) (p = 0.01) and CD (p = 0.04). Allele frequencies of the OCTN1/2 variants were significantly higher in IBD/CD cases (p<0.04). The homozygous mutant OCTN1/2 haplotype was increased in IBD (24.3% v 16.1%, p = 0.02) and UC (28.2% v 16.1%, p = 0.02) compared with controls. The OCTN1/2 variants were not independent of the background IBD5 risk haplotype in conferring disease susceptibility. Unifactorial analysis in CD patients showed that carriage of the TC haplotype was associated with lower weight, height, and BMI centile (<9(th) centile) at diagnosis (weight: 87.9% v 67.3% (p = 0.002), odds ratio (OR) = 3.52 (95% confidence interval, 1.51 to 8.22); height: 84.1% v 68.4% (p<0.05), OR = 2.44 (1.00 to 5.99); BMI: 79.6% v 61.1% (p = 0.02), OR = 2.49 (1.14 to 5.44)), and lower weight centile at follow up (87.5% v 64.6% (p = 0.03), OR = 3.83 (1.03 to 14.24)). Multifactorial binary logistic regression analysis confirmed association of the TC haplotype with lower weight centile at diagnosis (p = 0.02, OR = 3.41 (1.20 to 9.66)).

CONCLUSIONS

These data implicate variants within the IBD5 haplotype, as determinants of disease susceptibility and growth indices in early onset IBD. The OCTN1/2 variants remain potential positional candidate genes, but require further analysis.

DLG5 variants do not influence susceptibility to inflammatory bowel disease in the Scottish population

INTRODUCTION

Recent data have suggested that specific haplotypic variants of the DLG5 gene on chromosome 10q23 may be associated with susceptibility to inflammatory bowel disease (IBD) in Germany. Haplotype D, notably characterised by the presence of a G-->A substitution at nucleotide 113, was associated with susceptibility to Crohn's disease (CD) whereas an extended haplotype A conferred protection.

AIMS

Association of DLG5 haplotypic variants with disease susceptibility, genotype-phenotype relationships, and epistasis with CARD15 was investigated in the Scottish population.

PATIENTS AND METHODS

A total of 374 CD, 305 ulcerative colitis (UC), and 294 healthy controls (HC) were studied. Genotyping for the variants rs1248696 (113A, representing haplotype D) and the single nucleotide polymorphism tag rs2289311 (representing haplotype A) were typed using the Taqman system.

RESULTS

On analysis of the DLG5 variant 113A, there were no associations with IBD when allelic frequency (11.4% IBD v 13.2% HC; p = 0.30) and carrier frequency (19.2% IBD v 24.6% HC; p = 0.069) were analysed. No associations were observed between 113A variant allelic frequency (p = 0.37), carrier frequency (p = 0.057), and CD. In fact, 113A heterozygosity rates were lower in CD (16%) and IBD (16.9%) than in HC (23%) (p = 0.029 and p = 0.033, respectively). No associations between DLG5 and UC were observed. Haplotype A was not protective and there was no evidence of epistasis between DLG5 and CARD15.

CONCLUSIONS

The present data contrast strongly with previous data from Germany. DLG5 113A is not associated with disease susceptibility and haplotype A does not confer resistance. Further work is required to evaluate the significance of DLG5 in other populations from geographically diverse regions.

Identifying suitable temperate forage legume species for saline areas

Summary. The salt tolerance of 29 lines of annual and perennial forage legume species was evaluated in 4 separate experiments over 0–100 mol NaCl/m3 in the greenhouse with the aim of identifying genetic material that is more salt tolerant than the more traditionally grown forage legume species. Several species or lines showed potential as salt-tolerant germplasm including Trifolium tomentosum, 2 lines of T. squamosum and T. alexandrinum cvv. Mescani and Wardan which were all more salt tolerant than T. subterraneum. Two lines of Lotus tenuis and 1 line of L. corniculatus were also relatively salt tolerant. Some of this material had never been assessed before under saline conditions. In contrast, several other species (T. arvense, T. vesiculosum, T. angustifolium and T. pratense) were found to be extremely salt sensitive and/or produced very small amounts of dry matter over all NaCl concentrations. We believe that further selection and field evaluation (including selection for increased productivity and salt tolerance over a range of growth stages) is required for the material that showed potential in order to fully assess its performance under saline soil conditions.

Identifying suitable grass species for saline areas

The salt tolerance of 20 lines of perennial grasses, including both native Australian and introduced species, was evaluated in 3 separate experiments over 0-180 mol Na Cl/m3 in the greenhouse, with the aim of identifying material that may be grown productively in saline areas in Australia, particularly the Murray- Darling Basin. Lolium perenne cv. Victorian, a species that is recognised as having a moderate level of salt tolerance, was included in all experiments as a reference species. In relative terms (as defined by the rate of the decline in dry matter production under saline conditions), only 5 species or cultivars (Psathyrostachys juncea cvv. Mankota, Tetracan and Vinall, Pascopyrum smithii cv. Walsh and Thinopyrum elongatum cv. Tyrell) were more salt tolerant than L. perenne cv. Victorian. However, several species including the native species Enteropogon acicularis and Themeda triandra, and the introduced species Eragrostis curvula cv. Consol and Thinopyrum elongatum, produced more dry matter than L. perenne over NaCl concentrations ranging from 0 to 180 mol/m3. The salt tolerance of Danthonia richardsonii was very similar to that of L. perenne. It was concluded that Psathyrostachys juncea, Pascopyrum smithii, Enteropogon acicularis and D. richardsonii, may offer potential as salt-tolerant germplasm, however, further field studies are recommended in order to fully assess the response of this material to saline soil conditions.

Variation in yield potential and salt tolerance of selected cultivars and natural populations of Trifolium repens L

The effects of NaCl (0-60 mol m-3) on growth rates, dry matter production, leaf expansion, photosynthesis and tissue ion concentrations were evaluated in 10, widely sourced cultivars and five natural populations of Trifolium repens. Shoot dry matter in all cultivars was significantly reduced at NaCl concentrations greater than 20 mol m-3. The rate of yield decline was greater in those cultivars which had the highest yield under non-saline conditions. In all cultivars, shoot concentrations of Na and Cl increased significantly with increasing external NaCl concentrations, but the response of individual cultivars differed. Differences in the capacity to control the uptake and distribution of Na and Cl into the shoot were related to differences in salt tolerance. Four cultivars (Haifa, Irrigation, Ladino and Tamar), representing extremes in relative salt tolerance, were studied in detail. There were no significant differences in root growth or in the concentrations of Na and Cl in the roots between these cultivars when grown at 0 to 60 mol m-3 NaCl. Rates of leaf expansion and petiole elongation were significantly reduced by NaCl in Ladino and Tamar, which had lower salt tolerance, but were not reduced greatly in Haifa and Irrigation, the two cultivars with higher tolerance. Individual leaf photosynthesis rates were not sensitive to NaCl and did not differ between cultivars. There were no significant differences in shoot yields or in shoot ion concentrations between five populations of T. repens, collected from the Mediterranean Region, and the control cultivar Haifa, although two populations (9028 and 9494) produced more dry matter at 60 mol m-3 NaCl. The plant-to-plant variation for all measured characters was large within both populations and cultivars. This study showed that genotypes which have greater salt tolerance or greater yield potential under non-saline conditions can be selected in order to maximize the yield of T. repens under moderately saline conditions.

The effect of NaCl on the establishment and growth of balansa clover (Trifolium michelianum Savi var. balansae Boiss.)

The effect of NaCl on the germination, seedling emergence and growth of established plants of balansa clover, Trifolium michelianum Savi var. balansae Bois. cv. Paradana was studied and compared with plants of subterranean clover T: subterraneum L. cv. Clare. Balansa and subterranean clover had similar salt tolerances at germination and seedling emergence. However balansa clover suffered from poor seedling vigour even under non-saline conditions, and this resulted in a low number of emerged seedlings over all NaCl concentrations compared with subterranean clover. Established plants of balansa clover, despite a lower initial seedling yield, were significantly more salt tolerant (P < 0.001) and had a greater survival rate over a four month period at concentrations greater than 75 mol m-3 NaCl. Shoot concentrations of chloride and sodium increased with increasing salinity in both species, however concentrations were lower in balansa clover especially at higher NaCl concentrations (75 and 100 mol m-3 NaCl). It is concluded that whilst established stands of balansa clover may be able to withstand high concentrations of NaCl, the major limitation to its establishment and production in saline irrigation areas is its poor seedling emergence and vigour.

Germination and growth of Secale montanum Guss. in the presence of sodium chloride

The salt tolerance of Secale montanum varied at different growth stages. Tolerance during germination was high, with NaCl of more than 340 mol m-3 necessary to reduce germination by 50%. Seedling emergence was more sensitive to NaCl with a 50% reduction occurring at approximately 300 mol m-3. Up to 200 mol m-3aC1, all emerged seedlings reached the first leaf stage, although shoot dry weight of emerged seedlings at 200 mol m-3 NaCl was reduced to 64% of that of seedlings under non-saline conditions. During later plant growth, shoot growth (dry weight) had a salt tolerance threshold of 20 mol m-3 NaCl (electrical conductivity, ECw, of 2.7 mS cm-1). Subsequent yield decline up to approximately 100 mol m-3 NaCl (ECw, = 10.8 mS cm-1) was 6.7% of non-saline yield per mS cm-1 increase in ECw. At higher NaCl concentrations a more reciprocal form of yield decline occurred. Considerable plantto- plant variation for shoot dry weight existed in the presence of NaCl, indicating scope for selection to increase the tolerance of S. montanum. Osmotic adjustment was aided by a reduction in tissue water content under increasing NaCl and by the accumulation of sodium and chloride. Sodium was mainly accumulated in the roots, although the roots increased their selectivity for potassium over sodium. Chloride was mainly accumulated in the shoots. S. montanum could be classed as moderately salt tolerant, a tolerance similar to such pasture grasses as Lolium perenne, Phalaris aquatica and Festuca arundinacea.

Identification and selection for salt tolerance in lucerne (Medicago sativa L.)

Variation existed between plants of the lucerne (Medicago sativa L.) cultivar CUF 101 for dry matter production, shoot number and length, and leaf damage when grown for 70 days under 250 mM NaCl (15 h photoperiod, 20�C day, 10�C night). Salt tolerance evaluation using the criteria percentage leaf damage (percentage of total number of leaves with complete or partial necrosis) and length of the main shoot, isolated plants which showed salt tolerance of reasonably high heritability (h2=0.41). Two generations of recurrent selection for tolerance significantly increased the mean population tolerance without decreasing production under non-saline conditions. While both sodium and chloride concentrations of the shoot were lower in the tolerant than in less tolerant plants, chloride was more closely associated with salt tolerance than sodium. Sodium and chloride concentrations in the roots did not vary with the level of salt tolerance. No association of shoot and root potassium concentration with tolerance was evident. Selection for salt tolerance in lucerne plants using percentage leaf damage of less than 10% as the main criterion should give a rapid response to selection. The efficiency of selection may be increased if selection is based on the efficiency of chloride exclusion from the shoots and/or the level of chloride tolerated by the shoots prior to leaf damage becoming evident.