S. J. H. Van Deventer

Infliximab treatment induces apoptosis of lamina propria T lymphocytes in Crohn's disease

Background and aims: Treatment with infliximab induces remission in about 70% of patients with steroid refractory Crohns disease. Because Crohns disease is considered to be mediated by uncontrolled activation of mucosal T lymphocytes, we hypothesised that infliximab could induce apoptosis of T lymphocytes. Methods: Induction of apoptosis in vivo was studied in 10 patients with therapy refractory Crohns disease. In vitro, resting or stimulated Jurkat T cells were incubated with infliximab. Results: Infusion of infliximab (5 mg/kg) in steroid refractory patients with Crohns disease induced a clinical response in 9/10 patients but did not influence expression of activation markers, homing receptors, memory cells, Fas expression, or Bax/Bcl-2 expression on peripheral blood T lymphocytes. In contrast, a significant increase in CD3 and TUNEL positive cells within colonic biopsies was detected 24 hours after infusion of infliximab, suggesting that infliximab stimulates apoptosis of activated T lymphocytes but not of resting T cells. To test this hypothesis, the effects of infliximab on Jurkat T cells were investigated. We observed that infliximab induced apoptosis and an increase in the Bax/Bcl-2 ratio of CD3/CD28 stimulated Jurkat T cells but not of unstimulated Jurkat cells. Conclusions: Our data indicate that infliximab treatment causes a rapid and specific increase in apoptosis of T lymphocytes in the gut mucosa. These findings may explain the rapid and sustained therapeutic effects of infliximab in Crohns disease.

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.

The cytokine-mediated imbalance between coagulant and anticoagulant mechanisms in sepsis and endotoxaemia

Disseminated intravascular coagulation (DIC) is a frequently occurring complication of sepsis and may contribute to multiple organ failure. More insight into the pathogenesis of this derangement of the coagulation system is necessary to develop more effective therapeutic strategies for this condition. Recently, more detailed knowledge on the pathogenetic pathways involved in DIC has been obtained by the study of models of experimental bacteraemia and endotoxaemia in human subjects and non‐human primates. The mechanisms that lead to activation of coagulation, potentiated by the simultaneous depression of physiological inhibitory systems and to impaired function of the fibrinolytic system, are outlined in this review. In addition, the mediatory role of various cytokines in the derangement of coagulation is discussed.

Efficacy and long-term safety of alipogene tiparvovec (AAV1-LPLS447X) gene therapy for lipoprotein lipase deficiency: an open-label trial.

We describe the 2-year follow-up of an open-label trial (CT-AMT-011–01) of AAV1-LPLS447X gene therapy for lipoprotein lipase (LPL) deficiency (LPLD), an orphan disease associated with chylomicronemia, severe hypertriglyceridemia, metabolic complications and potentially life-threatening pancreatitis. The LPLS447X gene variant, in an adeno-associated viral vector of serotype 1 (alipogene tiparvovec), was administered to 14 adult LPLD patients with a prior history of pancreatitis. Primary objectives were to assess the long-term safety of alipogene tiparvovec and achieve a ⩾40% reduction in fasting median plasma triglyceride (TG) at 3–12 weeks compared with baseline. Cohorts 1 (n=2) and 2 (n=4) received 3 × 1011 gc kg−1, and cohort 3 (n=8) received 1 × 1012 gc kg−1. Cohorts 2 and 3 also received immunosuppressants from the time of alipogene tiparvovec administration and continued for 12 weeks. Alipogene tiparvovec was well tolerated, without emerging safety concerns for 2 years. Half of the patients demonstrated a ⩾40% reduction in fasting TG between 3 and 12 weeks. TG subsequently returned to baseline, although sustained LPLS447X expression and long-term changes in TG-rich lipoprotein characteristics were noted independently of the effect on fasting plasma TG.

HLA-DR and -DQ phenotypes in inflammatory bowel disease: a meta-analysis

BACKGROUND Susceptibility to inflammatory bowel disease (IBD) is partially genetically determined and the HLA class II genes are candidates for a role in genetic susceptibility to IBD, because their products play a central role in the immune response. Multiple studies have reported associations between HLA-DR or -DQ phenotypes and either ulcerative colitis or Crohn’s disease, but much of the data are still controversial. AIMS To estimate overall associations between HLA class II phenotypes and IBD, and to establish the relative risk conferred by HLA-DR and -DQ phenotypes by meta-analysis. METHODS Medline was searched for publications reporting on the relation between IBD and HLA class II phenotypes. Raw data were extracted by recalculating the number of phenotypes or the number of alleles of the main antigens. Odds ratios and confidence intervals were calculated according to the Mantel-Haenszel method. RESULTS DR2, DR9, and DRB1*0103 were positively associated with ulcerative colitis, and a negative association was found for DR4 and ulcerative colitis. For Crohn’s disease a positive association was found with DR7, DRB3*0301, and DQ4 and a negative association with DR2 and DR3. CONCLUSIONS Both ulcerative colitis and Crohn’s disease are associated with specific HLA class II phenotypes. Further analysis of these phenotypes and subgroup analysis may elucidate how these alleles contribute to susceptibility to IBD.

Interleukin 10 (Tenovil) in the prevention of postoperative recurrence of Crohn's disease

BACKGROUND AND AIMS New lesions of Crohns disease occur early after ileal or ileocolonic resection and ileocolonic anastomosis. We performed a double blind controlled trial to evaluate the safety and tolerance of recombinant human interleukin 10 (IL-10; Tenovil) in subjects operated on for Crohns disease. We also assessed the effect of Tenovil in preventing endoscopic recurrence 12 weeks after surgery. METHODS Patients with Crohns disease who underwent curative ileal or ileocolonic resection and primary anastomosis were randomised within two weeks after surgery to receive subcutaneous Tenovil 4 μg/kg once daily (QD) (n=22) or 8 μg/kg twice weekly (TIW) (n=21), or placebo (QD or TIW) (n=22). An ileocolonoscopy was performed after 12 weeks of treatment. RESULTS Compliance was excellent. The most frequently observed adverse events were mild and moderate in severity and equally distributed across treatment groups. Thirty seven patients in the pooled Tenovil group and 21 patients in the pooled placebo group were evaluable by endoscopy. At 12 weeks, 11 of 21 patients (52%) in the placebo group had recurrent lesions compared with 17 of 37 patients (46%) in the Tenovil group (ns). The incidence of severe endoscopic recurrence was similar in both groups (9%). CONCLUSION Tenovil treatment for 12 consecutive weeks in patients with Crohns disease after intestinal resection was safe and well tolerated. No evidence of prevention of endoscopic recurrence of Crohns disease by Tenovil was observed.

Treatment of Crohn's disease with recombinant human interleukin 10 induces the proinflammatory cytokine interferon gamma

Background: Interleukin 10 (IL-10) exerts anti-inflammatory actions by counteracting many biological effects of interferon γ (IFN-γ). Aims: To investigate this in humans, we studied the effects of human recombinant IL-10 administration on IFN-γ production by patient leucocytes. Furthermore, we assessed the IFN-γ inducible molecule neopterin and nitrite/nitrate serum levels, which are indicative of endogenous nitric oxide formation. Methods: As part of two placebo controlled double blind studies, we analysed patients with chronic active Crohns disease (CACD) who received either subcutaneous recombinant human IL-10 (n=44) or placebo (n=10) daily for 28 days, and patients with mild to moderate Crohns disease (MCD) treated with either subcutaneous IL-10 (n=52) or placebo (n=16) daily for 28 days. Neopterin and nitrite/nitrate concentrations were measured in serum, and ex vivo IFN-γ formation by lipopolysaccharide or phytohaemagglutinin (PHA) stimulated whole blood cells were investigated before, during, and after IL-10 therapy. Results: In patients with CACD, the highest dose of 20 μg/kg IL-10 caused a significant increase in serum neopterin on days +15 and +29 of therapy compared with pretreatment levels. No changes were observed for nitrite/nitrate levels under either condition. In MCD, treatment with 20 μg/kg IL-10 resulted in a significant increase in PHA induced IFN-γ production. Conclusions: High doses of IL-10 upregulate the production of IFN-γ and neopterin. This phenomenon may be responsible for the lack of efficacy of high doses of IL-10 in the treatment of CACD and MCD.

Serum concentrations of cytokines in patients with active tuberculosis (TB) and after treatment

During TB cytokines play a role in host defence. To determine the cytokine pattern during various disease stages of TB, serum levels of IL‐12, interferon‐gamma (IFN‐γ), IL‐4, IL‐6 and IL‐10 were measured in 81 patients with active TB, 15 patients during therapy and 26 patients after anti‐tuberculous therapy as well as in 16 persons who had been in close contact with smear‐positive TB and in 17 healthy controls. IFN‐γ was elevated during active TB when compared with healthy controls, declining during and after treatment. IL‐12 (p40 and p70) serum levels were not significantly higher in patients with active TB compared with any of the other groups. IL‐4 levels were low in all groups. IL‐6 and IL‐10 serum levels were elevated in patients with active TB and during treatment. In patients with active TB serum levels of IFN‐γ and IL‐6 were higher in patients with fever, anorexia and malaise. IL‐12 levels were higher in patients with a positive smear. Cytokine levels did not correlate with localization of TB (pulmonary versus extrapulmonary), or skin test positivity. Cytokines directing a Th1 response (IL‐12) or a Th2 response (IL‐4) were not elevated in sera of this large group of patients with pulmonary and extrapulmonary TB. In patients with active TB, cytokines that were elevated in serum were IFN‐γ, IL‐6 and IL‐10.

Sonic hedgehog expression correlates with fundic gland differentiation in the adult gastrointestinal tract

Background: Sonic hedgehog (Shh) is an important endodermal morphogenetic signal during the development of the vertebrate gut. It controls gastrointestinal patterning in general, and gastric gland formation in particular. We have previously shown that Shh regulates gastric gland proliferation in the adult but detailed analysis of its expression along the adult gastrointestinal tract has never been undertaken. We therefore studied Shh expression along the normal human and rodent adult gastrointestinal tract as well as in intestinal metaplasia of the stomach, gastric and intestinal metaplasia of the oesophagus, and gastric heterotopia in Meckel’s diverticulum. Methods: The studies were performed with in situ hybridisation and by immunohistochemistry using an antibody that recognises the Shh precursor form. Results: We found that in the normal gastrointestinal tract, high levels of Shh were expressed in the fundic glands of the stomach. Shh expression was also found in fundic gland metaplasia and heterotopia. However, Shh expression was lost in intestinal metaplasia of the stomach. Conclusion: We found a strong correlation between Shh expression and fundic gland differentiation. Our current study therefore provides evidence that in addition to its role in gastric epithelial development, Shh plays a unique role in gastric epithelial differentiation in adults.

Short chain fatty acids stimulate epithelial mucin 2 expression through differential effects on prostaglandin E(1) and E(2) production by intestinal myofibroblasts

Background: The mucus layer protects the gastrointestinal mucosa from mechanical, chemical, and microbial challenge. Mucin 2 (MUC-2) is the most prominent mucin secreted by intestinal epithelial cells. There is accumulating evidence that subepithelial myofibroblasts regulate intestinal epithelial cell function and are an important source of prostaglandins (PG). PG enhance mucin secretion and are key players in mucoprotection. The role of bacterial fermentation products in these processes deserves further attention. Aims: We therefore determined whether the effect of short chain fatty acids (SCFA) on MUC-2 expression involves intermediate PG production. Methods: Both mono- and cocultures of epithelial cells and myofibroblasts were used to study the effects of SCFA on MUC-2 expression and PG synthesis. Cell culture supernatants were used to determine the role of myofibroblast derived prostaglandins in increasing MUC-2 expression in epithelial cells. Results: Prostaglandin E1 (PGE1) was found to be far more potent than PGE2 in stimulating MUC-2 expression. SCFA supported a mucoprotective PG profile, reflected by an increased PGE1/PGE2 ratio in myofibroblast supernatants and increased MUC-2 expression in mono- and cocultures. Incubation with indomethacin revealed the latter to be mediated by PG. Conclusions: SCFA can differentially regulate PG production, thus stimulating MUC-2 expression in intestinal epithelial cells. This mechanism involving functional interaction between myofibroblasts and epithelial cells may play an important role in the mucoprotective effect of bacterial fermentation products.