Review article: maintenance treatment of Crohn's disease.

The aetiology of Crohn's disease is unknown and therefore no curative treatments are available for the disease. The natural history of Crohn's disease is characterized by recurrent flare-ups of symptoms. Several drug treatments are effective in inducing clinical remission. However, no drug treatments are available in order to prevent clinical relapses, although several drug regimens may delay clinical flare-ups. Crohn's disease treatment for maintaining clinical remission needs to be tailored in relation to specific characteristics of each patient. The frequency of clinical relapse indeed shows marked variations in subgroups of patients, as the likelyhood of relapse is higher in patients in clinical remission for less than 6 months. Treatment strategies for maintaining remission may therefore differ among inactive patients. In chronically active, steroid-dependent or steroid-refractory Crohn's disease patients immunomodulatory drugs (azathioprine 2-2.5 mg/kg by mouth, 6-mercaptopurine 1-1.5 mg/kg by mouth, or methotrexate 15-25 mg/i.m./week) should be added to oral mesalazine (2.4 g/day), while in long-term inactive Crohn's disease patients mesalazine alone may be effective in delaying relapse. Recently, treatment with anti-tumour necrosis factor-alpha monoclonal antibodies (Infliximab or CDP571) has shown efficacy in delaying relapse in responsive patients. One other issue which needs to be considered before selecting drug treatments for maintaining remission in Crohn's disease, is that Crohn's disease activity is currently assessed on the basis of standard clinical scores which may not appropriately reflect the biological activity of the disease. Clinical remission as defined by standardized scores may include heterogeneous subgroups of patients showing different endoscopic and histological activity or persistence of activated immunocompetent cells within the gut. Several sub-clinical markers of relapse have indeed been reported in quiescent Crohn's disease, although their usefulness in clinical practice in currently uncertain.

Role of platelet activating factor in hemodialysis.

A complex array of inflammatory mediators are generated as a consequence of blood contact with hemodialysis (HD) membranes. Beside complement activation, other mediators are involved in cell activation, and are thought possibly to be responsible for early and long-term multiple changes in immunity infection, hypercatabolism, beta 2-microglobulin generation and hemostatic mechanisms. Previous studies from our laboratories have established platelet activating factor (PAF) as one of the mediators generated by complement-dependent or independent mechanisms of cell interaction with hemodialysis membranes. Recent studies on the production of PAF from endotoxin-primed polymorphonuclear neutrophils in a closed miniaturized circuit, and on the effect of PAF in mediating endotoxin- and cytokine-induced leukocyte adherence to HD membranes, highlight so far undescribed new roles of this mediator in biocompatibility.

Salivary specific IgG is a sensitive indicator of the humoral immune response to Helicobacter pylori.

In humans, salivary antibodies are secreted during humoral immune response. Helicobacter pylori infection is associated with systemic humoral immune response reflected by raised serum levels of specific IgG. The present study was aimed at exploring whether salivary concentrations of specific H. pylori IgG are a reliable indicator of H. pylori infection. Serum and salivary samples were obtained from 291 subjects attending the GI clinic and tested for H. pylori-specific IgG by a direct ELISA (94% sensitivity, 95% specificity for serum determinations) using a crude H. pylori sonicate as antigen. Data are given as optical density (mean +/- S.D.). Levels of salivary H. pylori IgG paralleled those of circulating specific IgG in the 291 subjects studied (0.981 +/- 0.431 vs. 0.777 +/- 0.682, respectively). A significant positive correlation was found between specific H. pylori IgG in sera and saliva samples (r = 0.981, P < 0.0001). An overall concordance between circulating and salivary H. pylori IgG was observed in 238 out of the 291 (81.7%) subjects. Salivary H. pylori IgG represent a sensitive marker of specific humoral immune response and they may substitute circulating H. pylori IgG measurement when sera samples are not available.

Isotypic analysis of specific antibody response in serum, saliva, gastric and rectal homogenates of Helicobacter pylori-infected patients.

The relationship between systemic and local humoral immune response to Helicobacter pylori is poorly understood. To further address this issue we measured, using ELISA, H. pylori-specific IgG and IgA antibodies in serum, saliva, gastric and rectal homogenates of H. pylori-infected patients. A total of 107 patients who underwent upper GI endoscopy and/or sigmoidoscopy were studied. The isotypic pattern of H. pylori-specific antibodies appeared to differ at the serum, salivary, gastric and rectal mucosa level. Serum H. pylori IgG titers were higher than those of the serum-specific IgA. On the contrary, in saliva samples H. pylori IgA titers were higher than specific IgG titers. In gastric homogenates, specific IgG and IgA titers were similar. H. pylori-specific IgG were detectable in rectal homogenates but no or very low H. pylori-specific IgA were found in the same material. Furthermore, no difference was found in H. pylori IgG and IgA in serum, saliva and gastric homogenates between duodenal ulcer and non-ulcer dyspepsia patients. Data of the present study indicate that, in H. pylori-infected patients, the specific immune response is as follows: (1) it involves the secretory immune system; (2) it is paralleled by the specific salivary IgA; (3) it does not differentiate duodenal ulcer from non-ulcer dyspepsia patients; and (4) it does not take place in the large bowel.

Evidence against an increased risk of Helicobacter pylori infection in dentists: a serological and salivary study.

BACKGROUND: An oral-to-oral route of transmission of Helicobacter pylori infection has been postulated, which is supported by the observation that H. pylori is present in the saliva and in dental plaque. On the basis of this assumption, an increased risk of H. pylori infection among dentists was postulated. METHOD: Serum and salivary H. pylori immunoglobulin (lg)G antibodies were measured in a group of practising dentists. For comparison we also studied a group of controls from the same urban area matched for age, sex, smoking habits, alcohol and non-steroidal anti-inflammatory drug consumption, and history of dyspepsia. RESULTS: There was no significant difference in serum H. pylori lgG antibodies titres between dentists and controls [optical density (OD) 0.991 +/- 0.588 versus 1.025 +/- 0.591, respectively]. Salivary H. pylori lgG were 0.693 +/- 0.726 and 0.661 +/- 0.614 OD in the dentists and control groups, respectively. The frequency of H. pylori-seropositive subjects did not differ between the two groups [22 out of 39 (56%) versus 46 out of 71 (64%)]. A positive saliva assay was found in 23 out of 39 (59%) dentists and in 44 out of 71 (62%) controls. The odds ratio for a dentist being H. pylori-positive was 0.7 (95% confidence interval 0.3-1.7) by serology and 0.9 (95% confidence interval 0.4-2.1) by salivary antibody assay. CONCLUSION: The data of this study do not support the concept that dentists are a high-risk group for H. pylori infection.

Salivary-specific immunoglobulin G in the diagnosis of Helicobacter pylori infection in dyspeptic patients.

OBJECTIVES: Helicobacter pylori infection is arguably the most common chronic bacterial infection in humans. The high prevalence and the association with peptic ulceration and gastric cancer indicate that simple, noninvasive methods for diagnosis of the infection are needed. In this study, the accuracy of salivary diagnosis for H. pylori infection was assessed. METHODS: Saliva and serum samples of 152 dyspeptic patients were tested for H. pylori IgG and IgA by an in-house ELISA. All patients underwent gastroscopy with biopsy. RESULTS: One hundred thirty-one patients (86%) were found to be H. pylori positive on histology. Duodenal ulcer was found in 67 patients; 85 had no macroscopic lesion. Salivary and serum H. pylori IgG as well as serum H. pylori IgA titers were significantly higher in H. pylori-positive than in H. pylori-negative patients. The sensitivity and specificity of salivary H. pylori IgG were 82% and 71%, respectively; the positive and negative predictive values were 95% and 40%, respectively; and the accuracy 81%. The corresponding figures for serum H. pylori IgG were 97% and 91%; 98% and 83%; and 96%. Those for serum H. pylori IgA were 80% and 52%; 91% and 30%; and 76%. The sensitivity of salivary H. pylori IgG in detecting duodenal ulcer was 83% (56/67) that of serum H. pylori IgG was 97% (65/67) (odds ratio = 0.15; confidence interval = 0.02-0.8; p = 0.02). CONCLUSIONS: Salivary H. pylori IgG was a fairly sensitive and accurate indicator of gastric H. pylori colonization, with a high positive predictive value in our population. Data, however, suggest that salivary H. pylori IgG measurements do not compare favorably with serology.

Mucosal and systemic antibody levels against Helicobacter pylori do not parallel gastric inflammatory changes.

BACKGROUND AND AIMS: Mucosal and systemic antibodies against Helicobacter pylori have been detected but their role in the natural history of Helicobacter pylori-related diseases is unclear. In this study, the levels of Helicobacter pylori IgG and IgA were related to the grade of gastritis. PATIENTS AND METHODS: A series of 152 dyspeptic patients underwent gastroscopy with biopsies. Helicobacter pylori was detected in 131 (86%) patients. Samples of serum and unstimulated saliva were collected. Helicobacter pylori IgG and IgA were measured in homogenised gastric biopsies, saliva and serum by an in-house enzyme linked immunosorbent assay. RESULTS: Levels of gastric mucosa, salivary and serum Helicobacter pylori IgG were higher (p < or = 0.01) in Helicobacter pylori positive than negative patients. Likewise, levels of gastric mucosa and serum Helicobacter pylori IgA were higher (p < 0.01) in Helicobacter pylori positive patients. Gastric mucosa, saliva and serum Helicobacter pylori antibody levels did not differ between superficial and atrophic, active and inactive Helicobacter pylori positive gastritis. CONCLUSIONS: These data indicate that gastric inflammatory changes may not necessarily be related to the antibody response against Helicobacter pylori.