Systematic review of dysplasia after restorative proctocolectomy for ulcerative colitis

Background

The aim of this systematic review was to assess the prevalence and site of dysplasia after restorative proctocolectomy (RPC) for ulcerative colitis (UC), and to identify risk factors that could be used in a surveillance programme.

Methods

Medical databases were searched for potentially relevant publications between 1978 and 2006. Studies that dealt with RPC for UC and postoperative surveillance were included. Two researchers independently performed study selection, quality assessment, data extraction and analysis.

Results

Twenty-three observational studies and case series were included, with a total of 2040 patients. The pooled prevalence of confirmed dysplasia in the pouch, anal transitional zone or rectal cuff was 1·13 (range 0–18·75) per cent. The prevalence of high-grade dysplasia, low-grade dysplasia and indefinite for dysplasia was 0·15 (range 0–4·49), 0·98 (range 0–15·62) and 1·23 (range 0–25·28 per cent) respectively. Dysplasia was equally frequent in the pouch and rectal cuff or anal transitional zone. Dysplasia and cancer identified before or at operation seemed to be significant predictors of the development of dysplasia. Pouchitis and duration of follow-up were not of predictive value.

Conclusion

Although based on low-level evidence from uncontrolled studies, the prevalence of dysplasia observed after RPC was remarkable. A surveillance programme that takes into account the risk factors found is therefore advocated.

Prediction of antitumour necrosis factor clinical efficacy by real-time visualisation of apoptosis in patients with Crohn's disease

BACKGROUND

The human anti-tumour necrosis factor (TNF) antibody infliximab binds to the membrane TNF and subsequently induces apoptosis of activated lamina propria T lymphocytes in patients with Crohn's disease in vitro.

AIM

To test whether the ability of rapid anti-TNF-induced apoptosis in the gut predicts the efficacy of anti-TNF treatment in inflammatory bowel disease.

METHODS

(99m)Technetium-annexin V single-photon emission computer tomography (SPECT) was performed in 2 models of murine experimental colitis and in 14 patients with active Crohn's disease as assessed by the Crohńs Disease Activity Index (CDAI) to study the effect of anti-TNF treatment on apoptosis in the intestine during active colitis. Disease activity was evaluated 2 weeks after infliximab infusion using the CDAI (definition response: drop of >100 points).

RESULTS

Colonic uptake of (99m)Tc-annexin V significantly increased in 2,4,6-trinitrobenzene sulphonate-induced colitis as well as in transfer colitis on administration of anti-TNF antibodies compared with a control antibody as determined with dedicated animal pinhole SPECT. In addition, uptake of (99m)Tc-annexin V significantly increased in patients with active Crohn's disease responding to infliximab treatment. Colonic (99m)Tc-annexin V uptake ratio (mean (SEM)) increased from 0.24 (0.03) to 0.41(0.07) (p<0.01), 24 h after infliximab infusion (5 mg/kg). A mean increase of 98.7% in colonic uptake of (99m)Tc-annexin V could be detected in 10 of the 14 responding patients (CDAI >100 points at week 2) compared with 15.2% in non-responding patients (p = 0.03). Analysis of the mucosal biopsy specimens identified lamina propria T cells as target cells undergoing apoptosis.

CONCLUSIONS

These in vivo observations support the notion that colonic uptake of (99m)Tc-annexin V correlates with clinical benefit of anti-TNF treatment and might be predictive of therapeutic success.

Narrow-band imaging compared with conventional colonoscopy for the detection of dysplasia in patients with longstanding ulcerative colitis

BACKGROUND AND STUDY AIM

Patients with longstanding ulcerative colitis are at increased risk of developing colorectal cancer. Colonoscopic surveillance is advised, but the detection of neoplasia by conventional colonoscopy is difficult. The aim of this study was to compare the accuracy of narrow-band imaging (NBI), a new imaging technique, with standard colonoscopy for the detection of neoplasia in patients with longstanding ulcerative colitis.

PATIENTS AND METHODS

This was a prospective, randomized, crossover study of 42 patients with longstanding ulcerative colitis. All participants underwent NBI and conventional colonoscopy with at least 3 weeks between the procedures. Randomization determined the order of the examinations. Targeted biopsies were taken during both procedures; additional random biopsies were taken at conventional colonoscopy only. The number of patients with neoplasia detected by targeted biopsies was used to assess the sensitivity for each technique.

RESULTS

With NBI, 52 suspicious lesions were detected in 17 patients, compared with 28 suspicious lesions in 13 patients detected during conventional colonoscopy. Histopathological evaluation of targeted biopsies revealed 11 patients with neoplasia: in four patients the neoplasia was detected by both techniques, in four patients neoplasia was detected only by NBI, and in three patients neoplasia was detected only by conventional colonoscopy ( P = 0.705). Aside from targeted biopsies, 1522 random biopsies were taken. These revealed one additional patient with dysplasia that was not detected by either technique.

CONCLUSIONS

The sensitivity of the studied first-generation NBI system for the detection of patients with neoplasia seems to be comparable to conventional colonoscopy, although more suspicious lesions were found during NBI. We believe that it is still too early to stop taking additional random biopsies at surveillance colonoscopy in patients with ulcerative colitis.

Pancytopenia due to high 6-methylmercaptopurine levels in a 6-mercaptopurine treated patient with Crohn's disease

In a 23-year-old female with colonic Crohn's disease 6-mercaptopurine 100 mg daily (1.7 mg/kg) was added to mesalamine and prednisolone therapy because of ongoing disease activity. One month later she had fever and a pancytopenia. 6-methylmercaptopurine ribonucleotides levels were extremely elevated (57,000 pmol/8x10(8) red blood cells) and 6-thioguanine nucleotides levels were subtherapeutically (126 pmol/8x10(8) red blood cells). Genotyping showed a wildtype thiopurine S-methyltransferase TPMT(H/H) (*1/*1) genotype and a wildtype inosine triphosphate pyrophosphatase gene. TPMT and inosine triphosphate pyrophosphatase activity were normal. The pancytopenia recovered spontaneously within a few weeks, parallel with decreasing 6-methylmercaptopurine ribonucleotides levels after interrupting 6-mercaptopurine treatment. Epstein-Barrvirus, Cytomegalovirus and Herpesvirus infections were excluded by serology. This is the first report of pancytopenia due to extremely high 6-methylmercaptopurine ribonucleotides levels. No relation was found with the genotype of TPMT and inosine triphosphate pyrophosphatase enzymes, which play key roles in the thiopurine metabolic pathway. Apparently, 6-methylmercaptopurine ribonucleotides metabolites can cause pancytopenia, as was already known for 6-thioguanine nucleotides.

Review article: thiopurines in inflammatory bowel disease

BACKGROUND

In the past 10-20 years, knowledge of both thiopurine pharmacology and -pharmacogenetics has been extended dramatically and used to develop new strategies to improve efficacy and reduce toxicity.

AIM

To review thiopurine efficacy, toxicity, pharmacology, pharmacogenetics, interactions in patients with inflammatory bowel disease. Special attention was paid to new strategies for optimization of pharmacotherapy.

METHODS

To collect relevant scientific articles, a Pubmed search was performed from 1966 through January 2006 with the following key words (MeSH terms preferentially) in multiple combinations: 'azathioprine', '6-mercaptopurine', '6-MP', '6-thioguanine', '6-TG', 'thiopurine(s)', 'metabolites', 'level(s)', 'TDM', 'TMPT', 'ITPA', 'genotype(s)', 'phenotype(s)', 'inflammatory bowel disease', 'Crohn('s) disease', 'ulcerative colitis'.

RESULTS

Strategies for optimization of pharmacotherapy include therapeutic drug monitoring of thiopurine metabolites, geno- or phenotyping crucial enzymes in thiopurine metabolism like thiopurine S-methyltransferase and inosine triphosphate pyrophosphatase, and the use of thioguanine as such.

CONCLUSIONS

Thiopurine S-methyltransferase genotyping and therapeutic drug monitoring are useful instruments for individualizing thiopurine pharmacotherapy of inflammatory bowel disease. Inosine triphosphate pyrophosphatase genotyping may be helpful in case of unexplainable myelotoxicity. In case of azathioprine- or mercaptopurine-intolerance, thioguanine seems a promising alternative. However, more knowledge needs to be gathered about its potential hepatotoxicity.

A dose escalating, placebo controlled, double blind, single dose and multidose, safety and tolerability study of fontolizumab, a humanised anti-interferon gamma antibody, in patients with moderate to severe Crohn's disease

INTRODUCTION

This study was designed to evaluate the safety of fontolizumab, a humanised anti-interferon gamma antibody, in patients with moderate to severe Crohn's disease (CD).

PATIENTS AND METHODS

Forty five patients with a CD activity index (CDAI) of 250-450 were randomised in a double blind, placebo controlled, dose escalating fashion to receive single doses of fontolizumab (0.1, 1.0, and 4.0 mg/kg) or placebo. By day 29, patients with clinical response were re-randomised to receive three additional doses of one half their initial fontolizumab dose or placebo at four weekly intervals. Primary objectives were safety and tolerability. Secondary outcomes included assessments of immunogenicity, clinical activity, and potential pharmacodynamic surrogates.

RESULTS

Treatment was generally well tolerated. There were slightly more reports of chills, flu-like syndrome, asthenia, nausea, and vomiting in the 1.0 mg and 4.0 mg/kg fontolizumab cohorts. Two serious adverse events rated as worsening of CD occurred under fontolizumab. Antibodies to fontolizumab were confirmed in one patient. No differences in clinical activity parameters were noted between any of the active treatment groups and placebo, with the placebo group having a particularly favourable outcome (60% response and 40% remission). By day 29, a more enhanced decrease in median Crohn's disease endoscopic index of severity (p = 0.02) and serum C reactive protein (p<0.001) was observed in the 4.0 mg/kg (n = 14) fontolizumab cohort compared with placebo (n = 10). Pharmacodynamic effects were observed by immunohistochemistry.

CONCLUSIONS

Fontolizumab was well tolerated with minimal immunogenicity at doses of up to 4.0 mg/kg in patients with CD. A biological activity of fontolizumab is suggested.

Fontolizumab, a humanised anti-interferon gamma antibody, demonstrates safety and clinical activity in patients with moderate to severe Crohn's disease

INTRODUCTION

Interferon gamma is a potent proinflammatory cytokine implicated in the inflammation of Crohn's disease (CD). We evaluated the safety and efficacy of fontolizumab, a humanised anti-interferon gamma antibody, in patients with moderate to severe CD.

METHODS

A total of 133 patients with Crohn's disease activity index (CDAI) scores between 250 and 450, inclusive, were randomised to receive placebo or fontolizumab 4 or 10 mg/kg. Forty two patients received one dose and 91 patients received two doses on days 0 and 28. Investigators and patients were unaware of assignment. Study end points were safety, clinical response (decrease in CDAI of 100 points or more), and remission (CDAI < or =150).

RESULTS

There was no statistically significant difference in the primary end point of the study (clinical response) between the fontolizumab and placebo groups after a single dose at day 28. However, patients receiving two doses of fontolizumab demonstrated doubling in response rate at day 56 compared with placebo: 32% (9/28) versus 69% (22/32, p = 0.02) and 67% (21/31, p = 0.03) for the placebo, and 4 and 10 mg/kg fontolizumab groups, respectively. Stratification according to elevated baseline C reactive protein levels resulted in a decreased placebo response and pronounced differences in clinical benefit. Two grade 3 adverse events were reported and were considered to be related to CD. One death (during sleep) and one serious adverse event (an elective hospitalisation) occurred, both considered unrelated.

CONCLUSION

Treating active CD with fontolizumab was well tolerated and resulted in increased rates of clinical response and remission compared with placebo.

Guidelines for treatment with infliximab for Crohn's disease

Infliximab is an accepted induction and maintenance treatment for patients with Crohn's disease. The effectiveness of infliximab has been demonstrated for both active luminal disease and for enterocutaneous fistulisation. In addition, infliximab can be administered for extraintestinal symptoms of Crohn's disease, such as pyoderma gangrenosum, uveitis and arthropathy. Maintenance treatment with infliximab is effective and is regarded as safe as long as the necessary safety measures are heeded. Infusion reactions occur in 3 to 17% of the patients and are associated with the formation of antibodies to infliximab. A reduction in infusion reactions is possible by the concurrent administration of steroids and the use of immunosuppressants (azathioprine, 6-mercaptopurine, methotrexate). Furthermore, immunosuppressants increase the duration of the response to infliximab. For these reasons, the concomitant use of immunosuppressants with infliximab is recommended. Infections and most specifically tuberculosis need to be ruled out before infliximab is administered. Up to now, there are no indications for a connection between an increased risk for malignancies and treatment with infliximab.

Pharmacogenetics of thiopurine therapy in paediatric IBD patients

BACKGROUND

Azathioprine is widely used in the treatment of children with inflammatory bowel disease. The occurrence and type of adverse events to azathioprine may be related to thiopurine S-methyltransferase (TPMT) enzyme activity and to inosine triphophate pyrophosphatase (ITPase) deficiency.

AIM

Investigate frequencies of functional TPMT polymorphisms and ITPA polymorphisms and their association with the occurrence of adverse events during azathioprine therapy in a paediatric inflammatory bowel disease population.

METHODS

Seventy-two azathioprine treated paediatric inflammatory bowel disease patients, 47% girls, mean age 12.5 years (range 6.5-17.5), were assessed for TPMT and ITPA polymorphisms and for adverse events. The relation between polymorphisms and adverse events is evaluated.

RESULTS

Of all azathioprine treated patients, 11 experienced an adverse event for which azathioprine was stopped: pancreatitis (n = 4), leucopenia (n = 2) and 'general malaise' (n = 5). Of the 11 patients who stopped azathioprine because of adverse events, 10 had wild-type alleles for all investigated genotypes. Genotyping of ITPA 94C>A polymorphisms showed that two patients were homozygous, both tolerated azathioprine well.

CONCLUSIONS

No association of functional ITPA and TPMT polymorphisms and the occurrence of azathioprine related adverse events could be detected. Pharmacogenetic assessment prior to thiopurine therapy does not seem warranted.

European evidence based consensus on the diagnosis and management of Crohn's disease: special situations

This third section of the European Crohn's and Colitis Organisation (ECCO) Consensus on the management of Crohn's disease concerns postoperative recurrence, fistulating disease, paediatrics, pregnancy, psychosomatics, extraintestinal manifestations, and alternative therapy. The first section on definitions and diagnosis reports on the aims and methods of the consensus, as well as sections on diagnosis, pathology, and classification of Crohn's disease. The second section on current management addresses treatment of active disease, maintenance of medically induced remission, and surgery of Crohn's disease.

Inosine triphosphate pyrophosphatase and thiopurine s-methyltransferase genotypes relationship to azathioprine-induced myelosuppression

BACKGROUND & AIMS

The use of azathioprine (AZA) in inflammatory bowel disease (IBD) patients is limited by toxicity, which occurs in up to 20% of treated patients. Mutations in the thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) genes have been associated with the occurrence of AZA-related toxicity. The aim of our study was to determine the relative contribution of ITPA and TPMT mutations to the development of toxicity induced by AZA treatment in IBD patients.

METHODS

ITPA(94C>A, IVS2+21A>C) and TPMT (238G>C, 460G>A, and 719A>G) genotypes were assessed in 262 IBD patients (159 females, 103 males; 67 patients with ulcerative colitis, 195 patients with Crohn's disease) treated with AZA and were correlated with the development of leukopenia and hepatotoxicity.

RESULTS

Leukopenia (leukocyte count, <3.0 x 10(9)/L) was observed in 4.6% of treated patients. The frequencies of mutant ITPA 94C>A and TPMT alleles were significantly higher in the leukopenic population compared with patients without leukopenia (16.7% and 5.4%, respectively, for ITPA 94C>A, and 20.8% and 4%, respectively, for TPMT). Moreover, the ITPA 94C>A and TPMT mutations predicted leukopenia: ITPA 94C>A odds ratio, 3.504; 95% confidence interval, 1.119-10.971 (P = .046); TPMT odds ratio, 6.316; 95% confidence interval, 2.141-18.634 (P = .004). Neither TPMT nor ITPA genotype predicted hepatotoxicity.

CONCLUSIONS

ITPA 94C>A and TPMT polymorphisms are associated with AZA-related leukopenia in IBD patients.

[Pneumocystis pneumonia during infliximab treatment for active Crohn's colitis]

A 51-year-old man with Crohn's disease for 22 years presented with a dry cough, dyspnoea, fever and diarrhoea. He had steroid-resistant Crohn's disease. Because of nausea complaints, azathioprine was switched to methotrexate with concomitant infliximab induction therapy. During infliximab therapy, symptoms occurred for which the patient was hospitalised and Pneumocystis pneumonia (PCP) was diagnosed by examination of bronchoalveolar lavage fluid; it was successfully treated with co-trimoxazole and prednisolone. The exacerbation of the Crohn's colitis diminished. This is the first Dutch case history of PCP during combination therapy with prednisolone, methotrexate and infliximab. Infliximab treatment has been associated with an increased risk for infectious complications. For patients with Crohn's disease, one should consider giving PCP prophylaxis for the duration of lymphocytopenia on an individual basis, weighing the adverse effects ofco-trimoxazole against the risk of PCP. A CD4-cell count < 0.2 x 10(9)/l or a lymphocyte count < 0.6 x 10(9)/l may be used as a guide.

New cytokine therapeutics for inflammatory bowel disease

Conventional therapy for inflammatory bowel diseases rely on corticosteroids and 5-aminosalicylates combined with immunosuppressive agents for maintenance. These drugs are not always effective and may inflict serious side effects. Other therapies are therefore awaited. Infliximab, a monoclonal antibody against the pro-inflammatory cytokine TNF-alpha has been successfully applied as a treatment for Crohn's disease. The mechanism of action of this drug extends beyond the level of TNF-alpha scavenging and includes induction of apoptosis of effector cells. Numerous anti-TNF antibodies have been developed and are currently evaluated in clinical trials. Other targets for monoclonal antibodies include integrins and cytokines involved in T-cell differentiation and activation. Likewise recombinant proteins that moderate TNF bioactivity and lymphocyte function have been developed. The therapeutic effect of recombinant interleukin-10 seems to be dependent on local delivery of the protein. Antisense therapy targeting lymphocyte migration has also been tested in IBD. Finally, the conventional drug thalidomide and possibly MAP-kinase inhibitors may become novel treatment entities for IBD.

[Epstein-Barr virus-related lymphomas in patients with inflammatory bowel disease]

During treatment for inflammatory bowel disease (IBD) 2 men with ulcerative colitis, aged 52 and 38 years, and a 37-year-old man with Crohn's disease developed Epstein-Barr virus (EBV)-related non-Hodgkin's B-cell lymphoma. The first 2 patients underwent proctocolectomy and the use of immunosuppressive agents was discontinued, after which the lymphoma disappeared. The third patient had icterus, hepatosplenomegaly and pancytopenia; he died from multiple organ failure. Azathioprine and 6-mercaptopurine are first choice therapy in the treatment of steroid-refractory IBD. These immunomodulating agents are associated with the development of EBV-positive lymphomas in the setting of solid organ transplantation. This type of lymphoma is a rare complication in IBD, although the incidence in referral centres appears to be increasing. Since azathioprine is an important drug in IBD, there is a need for identification of IBD patients at risk of developing a lymphoma. EBV-DNA in plasma or in faeces may be a candidate tumour marker.

Recurrence after segmental resection for colonic Crohn's disease

Background

Segmental colonic resection is commonly performed in patients with colorectal Crohn's disease. The aim of this study was to evaluate the outcome after segmental colonic resection and to define risk factors for re-resection.

Methods

Consecutive patients who had an initial segmental colonic resection for Crohn's colitis between 1987 and 2000 were evaluated. Patients who underwent ileocolonic resection were excluded. Patient-, disease- and treatment-related variables were assessed as possible risk factors for disease recurrence.

Results

Ninety-one patients (62 women) with a median follow-up of 8·3 years were studied. Thirty patients (33 per cent) had at least one re-resection, of whom 20 finally underwent total (procto)colectomy. Female sex and a history of perianal disease were identified as independent risk factors for re-resection: odds ratio 12·52 (95 per cent confidence interval (c.i.) 2·38 to 65·84) and 13·94 (95 per cent c.i. 3·02 to 64·27) respectively. Forty (44 per cent) of the 91 patients had a stoma at the end of the study period. Of the 30 patients who had re-resection, 24 finally had a stoma.

Conclusion

Segmental resection for Crohn's colitis is justified. Recurrence is more frequent in women and in those with a history of perianal disease.

Targeting tumor necrosis factor-alpha in inflammatory bowel disease: why, how, and when?

A large proportion of patients with inflammatory bowel disease require more effective therapy, especially for the prevention of disease relapse. Recent therapeutic advances have focused on biologicals (monoclonal antibodies, therapeutic peptides, antisense oligonucleotides) that aim to neutralize specific proinflammatory proteins. This has proved successful for the anti-TNF-alpha antibody infliximab in patients with Crohn disease, but recent studies failed to demonstrate the efficacy of different anti-TNF-alpha strategies. Therefore, it seems essential to fully comprehend the molecular mechanisms of such compounds. An exciting development has been the association between drug efficacy and the induction of apoptosis in apoptosis-resistant lamina propria T cells in Crohn disease. Furthermore, TNF-alpha can also be targeted by "small molecules" to circumvent certain disadvantages of biologicals such as the nonoral route of administration, the potential immunogenicity, and the high costs of treatment. Several of these developments will certainly be relevant for designing future anti-TNF-alpha based strategies.

Infliximab therapy in Crohn's disease: safety issues

Infliximab has become a valuable addition to the therapeutic arsenal for Crohn's disease. Although the rate of adverse events was relatively low in the premarketing trials, several investigators have recently reported experience in large groups of patients. This has shed more light on safety aspects of infliximab therapy, which should change the approach towards patients prior to infliximab infusion. This review discusses some immunological aspects that are relevant for infliximab therapy and provides guidelines for daily practice.

Mitogen activated protein (MAP) kinase signal transduction pathways and novel anti-inflammatory targets

Over the last decade important advances have been made in our understanding of the molecular events underlying cellular responses to extracellular signals. Increased understanding of signal transduction mechanisms and gene regulation involved in immune responses has created opportunities for the discovery of novel therapeutic compounds useful in treating inflammatory disorders. One of the best studied signalling routes is the mitogen activated protein (MAP) kinase signal transduction pathway which plays a crucial role in many aspects of immune mediated inflammatory responses. Here, our current understanding of the MAP kinase pathway is reviewed, as well as recent advances in the design of novel agents that are able to modulate the activity of these signalling cascades.

Anti- and proinflammatory cytokines in the pathogenesis of tissue damage in Crohn's disease

Crohn's disease is a chronic inflammatory bowel disease of unknown origin. The understanding of the pathogenesis of inflammatory bowel diseases has been greatly advanced by manipulations of the immune system in mice using targeted disruptions of genes that encode specific anti- and proinflammatory cytokines, as well as T-cell subsets. The outcome of these experiments has implicated CD4+ lymphocytes and certain proinflammatory cytokines (tumour necrosis factor-alpha, interleukin-12) as playing a central role in the pathogenesis of mucosal inflammation in Crohn's disease. The present review focuses on these recent important immunological observations, and discusses several newly developed therapeutic strategies that are based either on blocking proinflammatory cytokines or on the administration of anti-inflammatory cytokines.

Beneficial effect of treatment with a monoclonal anti-tumor necrosis factor-alpha antibody on markers of coagulation and fibrinolysis in patients with active Crohn's disease

Crohn's disease has frequently been associated with coagulation abnormalities, causing intravascular deposition of fibrin and local infarction which can subsequently compromise the gut mucosa. Also, arterial and venous thromboembolic complications of larger vessels appear to be associated with Crohn's disease. Coagulation activation in patients with Crohn's disease could be a result of increased serum and tissue levels of cytokines, as reported. We prospectively studied parameters of coagulation and fibrinolysis in 10 patients with active Crohn's disease, who were subsequently treated with a monoclonal anti-tumor necrosis factor-alpha (TNF) antibody. Ten consecutive patients with active Crohn's disease (CDAI > 150), not responding to a daily dose of at least 20 mg prednisolone, received a single infusion of human/mouse chimeric anti-TNF antibody cA2. All evaluable patients attained complete clinical and endoscopic

Efficacy of recombinant granulocyte colony-stimulating factor (rhG-CSF) in experimental colitis

Inflammatory bowel disease is associated with mucosal neutrophil recruitment and activatation, mediated in part by arachidonic acid metabolites. G-CSF attenuates the immune response to sepsis and ameliorates glycogen storage disease Ib-related colitis. These actions may be effected through the shedding of neutrophil adhesion molecules, or inhibition of proinflammatory mediator synthesis. Immune complex colitis was used to evaluate the effect of rhG-CSF on colonic mucosal inflammation, neutrophil recruitment and the generation of eicosanoids. Immune complex colitis was induced in White New Zealand rabbits. Animals were pretreated with rhG-CSF either 24 h before induction, or at induction, with dosages of 50 and 200 micrograms/kg. rhG-CSF caused a time- and dose-dependent neutrophilia in all animals. Pretreatment with rhG-CSF resulted in increased tissue myeloperoxidase levels, despite a histologically similar mucosal polymorphonuclear cell infiltrate between treated and control colitis groups. Leukotriene B4 (LTB4) and thromboxane B2 (TXB2) dialysis fluid levels were lower in treated animals, in particular in the groups receiving two doses (LTB4: both P < 0.01; TXB2: both P < 0.01. Prostaglandin E2 (PGE2) levels in dialysis fluid of the rhG-CSF-treated animals showed no difference from controls. In this model of experimental colitis, high-dose therapy with G-CSF resulted in a marked decrease of proinflammatory mediators, but mucosal generation of the protective PGE2 was preserved. These results suggest that prolonged high-dose therapy with G-CSF may have anti-inflammatory effects in colitis.

Attenuation of the inflammatory response in an animal colitis model by neutrophil inhibitory factor, a novel beta 2-integrin antagonist

BACKGROUND

Neutrophils are significant effector cells in acute inflammatory bowel disease. Recruitment of these cells is dependent on beta 2-integrin-mediated adhesion and transmigration. The efficacy of neutrophil inhibitory factor (NIF), an antagonist of the beta 2-integrin CD11b/CD18, in ameliorating inflammation was tested in an animal model of acute colitis.

METHOD

Immune-complex colitis was induced in groups of rabbits by using various formalin concentrations (2%, 0.75%, and 0.5%). Animals were treated with rNIF, 10 mg/kg. After they had been killed the mucosal appearance was scored, and tissue saved for histology and quantitation of myeloperoxidase (MPO), leukotriene B4 (LTB4), prostaglandin E2 (PGE2), and thromboxane B2 (TXB2).

RESULTS

In the 2% formalin group therapy with rNIF resulted in lower LTB4 (p < 0.05) levels. For the 0.75% and 0.5% groups, MPO was lower with rNIF treatment (p < 0.03 and p < 0.05, respectively), as were LTB4 concentrations (both, p < 0.04). PGE2 and TXB2 levels remained unchanged. Histology showed polymorphonuclear cell infiltration to be reduced by rNIF in the 2% and 0.75% formalin-treatment groups (p < 0.05).

CONCLUSION

These results suggest that blockade of CD11b/CD18-mediated mucosal neutrophil recruitment may form part of a strategy for targeted therapeutic intervention in inflammatory bowel disease.