Drug Treatment of Inflammatory Bowel Disease

Bioinformatics analysis reveals transcriptome and microRNA signatures and drug repositioning targets for IBD and other autoimmune diseases

BACKGROUND

Inflammatory bowel disease (IBD) is a complex disorder involving pathogen infection, host immune response, and altered enterocyte physiology. Incidences of IBD are increasing at an alarming rate in developed countries, warranting a detailed molecular portrait of IBD.

METHODS

We used large-scale data, bioinformatics tools, and high-throughput computations to obtain gene and microRNA signatures for Crohn's disease (CD) and ulcerative colitis (UC). These signatures were then integrated with systemic literature review to draw a comprehensive portrait of IBD in relation to autoimmune diseases.

RESULTS

The top upregulated genes in IBD are associated with diabetogenesis (REG1A, REG1B), bacterial signals (TLRs, NLRs), innate immunity (DEFA6, IDO1, EXOSC1), inflammation (CXCLs), and matrix degradation (MMPs). The downregulated genes coded tight junction proteins (CLDN8), solute transporters (SLCs), and adhesion proteins. Genes highly expressed in UC compared to CD included antiinflammatory ANXA1, transporter ABCA12, T-cell activator HSH2D, and immunoglobulin IGHV4-34. Compromised metabolisms for processing of drugs, nitrogen, androgen and estrogen, and lipids in IBD correlated with an increase in specific microRNA. Highly expressed IBD genes constituted targets of drugs used in gastrointestinal cancers, viral infections, and autoimmunity disorders such as rheumatoid arthritis and asthma.

CONCLUSIONS

This study presents a clinically relevant gene-level portrait of IBD subtypes and their connectivity to autoimmune diseases. The study identified candidates for repositioning of existing drugs to manage IBD. Integration of mice and human data point to an altered B-cell response as a cause for upregulation of genes in IBD involved in other aspects of immune defense such as interferon-inducible responses.

Sulfasalazine and 5-aminosalicylic acid inhibit contractile leukotriene formation

Sulfasalazine, used therapeutically in the treatment of ulcerative colitis, is cleaved in vivo to form 5-aminosalicylic acid (5-ASA) and sulfapyridine. In an isolated preparation of rat peritoneal cells both sulfasalazine (IC50 = 0.15 mM) and 5-ASA (IC50 = 2.3 mM), but not sulfapyridine, inhibited calcium ionophore-stimulated formation of contractile leukotriene activity. This activity, although not identified directly, is attributable to a mixture of leukotriene C4 and leukotriene D4 (commonly referred to as SRS-A, or slow-reacting substance of anaphylaxis). Reference compounds evinced expected activities (IC50 = 0.024 mM for phenidone, IC50 = 0.3 microM for nordihydroguaiaretic acid, IC50 = 0.033 mM for BW 755C), whereas para-aminosalicylic acid and thiosalicylic acid were inactive. These properties of sulfasalazine may contribute to its therapeutic efficacy in vivo.

Adverse reactions to sulphasalazine and 5-amino salicylic acid in the same patient

We report a patient who developed sulphasalazine-related hepatitis with a subsequent adverse reaction to rectal 5-amino salicylic acid, in the form of pain and fever without associated liver dysfunction, suggesting reactions to both components of sulphasalazine. Included is a review of the literature. Caution should be observed when prescribing 5-amino salicylic acid to sulphasalazine-intolerant patients.

Steady-state kinetics of 5-aminosalicylic acid and sulfapyridine during sulfasalazine prophylaxis in ulcerative colitis

Fifteen adult and 19 pediatric outpatients with ulcerative colitis were studied to determine the steady-state kinetics of 5-aminosalicylic acid (5-ASA) released from salazosulfapyridine (SASP). Results of excretion in adults (mean 24-h recovery of 5-ASA, 21% in urine and 57% in feces) were compatible with those of healthy volunteers. Since mean SASP dose/kg body weight (about 50 mg/kg) and compliance (reflected in sulfapyridine recovery) were equal in adults and pediatric patients, the results of the patient groups could be compared. Near-complete azo reduction of SASP occurs in children. Absorption and excretion of 5-ASA and metabolism to acetyl-5-ASA did not differ statistically between pediatric and adult patients. However, the fecal excretion of the drug and its metabolites was significantly lower in young patients, although fecal concentrations were the same. The present results demonstrate that SASP is an excellent sustained-release drug for the delivery of 5-ASA to the lower part of the bowel system and provide a reference for comparison of 5-ASA kinetics after treatment with newer 5-ASA preparations.

5-Aminosalicylic acid in patients with an ileo-rectal anastomosis. A comparison of the fate of sulfasalazine and Pentasa

The pharmacokinetics of 5-aminosalicylic acid (5-ASA) from sulphasalazine (SASP) and the slow-release 5-ASA preparation Pentasa was investigated in a cross-over study in 9 otherwise healthy patients with an ileo-rectal anastomosis. The 24-hour recoveries of the drugs were 90.5% and 84.7%, respectively. The median release of 5-ASA from SASP was 50% and from Pentasa 75%. Equal amounts of 5-ASA (18.0% vs 17.9%) were found in the faeces, and a significantly larger amount (4.4% vs 28.9%) of the metabolite N-acetyl-5-aminosalicylic acid (ac-5-ASA) was found in faeces following Pentasa. A larger amount of 5-ASA was absorbed and subsequently excreted in the urine, mainly as the metabolite (2.5% vs 20.5%) from Pentasa. This confirms previous results in ileostomized patients treated with Pentasa. The present findings also demonstrate that bacterial azo-reduction of SASP in patients with ileorectal anastomosis may be an adequate way to deliver 5-ASA in this type of patient. Both treatments may be used in these patients during a flare up of ulcerative colitis, but randomized studies are needed.

Immune disorders of the gastrointestinal tract and liver

Immune disorders of the gastrointestinal tract and hepatobiliary systems comprise a diverse group of illnesses which share in common certain overlapping and yet distinctive expressions of cellular and humoral immunity. As is evident from material contained in this article, controversy and disparate results frequently characterize the study of immune mechanisms in a given disease process. Nonetheless, advances in quantitation of specific immunocyte function and phenotypic expression have greatly facilitated the depth of understanding of the immune process related to these disorders. Challenges for future clinical investigation of these disorders are to characterize cell-specific target antigens to which immunologic attack is directed and to unravel the immunogenetic mechanisms that trigger and direct immune-mediated injury to host tissues. It is anticipated that continued investigation of immune disorders of the gastrointestinal tract and liver will clarify pathogenetic mechanisms and thus permit formulation of rational and effective therapies.

Drug therapy of inflammatory bowel disease

Although the etiology of inflammatory bowel disease is unknown and specific therapy is unavailable, enough information on existing empiric agents is available to allow rational therapy. These agents include sulfasalazine, steroids, immunosuppressive drugs, metronidazole and cholestyramine. Sulfasalazine is a two-part molecule that depends on bacterial cleavage in the colon to deliver locally acting 5-aminosalicylate, whose mechanism of action may relate to inhibition of prostaglandin synthesis. The other half of the molecule, sulfapyridine, is responsible for most of the side effects of the drug. While the efficacy of sulfasalazine in the treatment and prevention of attacks of ulcerative colitis is well established, its use in Crohn's disease appears to be limited to patients with active colitis and ileo-colitis. Sulfasalazine is of major benefit in preventing relapses in patients with ulcerative colitis in remission. New formulations of 5-aminosalicylate may allow delivery of the apparently active moiety to the small bowel and colon without concomitant sulfapyridine toxicity. Corticosteroids are highly effective in acute attacks of ulcerative colitis and Crohn's ileitis and ileo-colitis; the mechanism of antiinflammatory action remains speculative. However, maintenance therapy with steroids is ineffective in preventing relapses or recurrent attacks of either ulcerative colitis or Crohn's disease. Steroid enemas allow topical administration to patients with distal colitis and proctitis with few systemic side effects. In children with growth failure associated with active Crohn's disease, amelioration by steroid therapy may actually restore normal growth. Immunosuppressive agents such as azathioprine and 6-mercaptopurine are of little value in active Crohn's disease when administered alone; however, in combination with other agents they may help diminish steroid dose, close fistulae and prevent relapse. Their mode of action likely depends on long-term cytostatic effects on immune effector cells. Concern for leukopenia and the development of late malignancy has limited their use to patients not responding to other therapies. Metronidazole, an antimicrobial agent that is effective against anaerobes, has recently been shown useful in Crohn's disease involving the colon and perianal area. Its mechanism of action is uncertain, but may be related to its antibacterial actions on anaerobes. Cholestyramine can be successfully used to control bile salt-induced diarrhea in Crohn's patients with terminal ileal resections. Effective drug therapy of inflammatory bowel disease is only part of a total program of management including reassurance, frequent explanation, well-timed use of surgery, and an understanding physician.

Sulfasalazine intolerance. A retrospective survey of the reasons for discontinuing treatment with sulfasalazine in patients with chronic inflammatory bowel disease

Sulfasalazine is of proven therapeutic value in chronic inflammatory bowel diseases (ulcerative colitis and Crohn's disease in the colon) of mild and moderate degrees. However, owing to adverse effects (allergy, dyspepsia), this drug often has to be withdrawn. The present work analyzes, in 704 patients with chronic inflammatory bowel disease, the frequency of such side effects that over a 15-year period necessitated withdrawal of sulfasalazine (Salazopyrin). A total of 17% of the patients developed dyspeptic manifestations, whereas extraintestinal manifestations, mainly exanthema and fever, occurred in 13%. Out of 121 patients with dyspeptic troubles, 107 had Salazopyrin replaced by EN Salazopyrin (dragées), and in 102 of them dyspepsia did not recur. Salazosulfadimidine (Azudimidine) was given to 48 patients who had developed extraintestinal manifestations when receiving sulfasalazine. Only 29% of these patients developed intolerance to this drug too. Generally, dyspepsia occurred within the first days after institution of treatment, extraintestinal manifestations after 1 to 3 weeks.

Intestinal lavage in the treatment of Crohn's disease: a pilot study

Taking into account that a damaged mucosal barrier may be responsible for the impairment and some systemic complications in Crohn's disease, we employed intestinal lavage as a therapeutic method in six patients suffering from active Crohn's disease. The results were compared with those obtained from a control group that received similar treatment with the exception of the lavage. Intestinal lavage was carried out with 18 1 of normal saline administered via a jejunal tube over a period of 2 h. The lavage procedure was tolerated well by all patients. A significant decrease of the Crohn's disease activity index and a significantly lower hospitalization time suggest a benefit in using the lavage method. Provided that these results can be confirmed in a larger series of patients, intestinal lavage may contribute to the strategy of conservative treatment of Crohn's disease.