-295 T-to-C promoter region IL-16 gene polymorphism is associated with Whipple's disease.

Whipple's disease (WD) is a rare systemic condition caused, in genetically predisposed subjects, by Tropheryma whipplei, a common bacterium widespread in the environment. The relevance of genetic predisposition in WD is shown by the association with HLA alleles DRB1*13 and DQB1*06 and by the demonstration that, in patients with WD, the cytokine genetic profile is skewed toward a Th2 and Treg response. Since IL-16 is involved in hampering the development of a protective macrophagic response against Tropheryma whipplei, we investigated whether the genetic background of IL-16 is different between patients with WD and controls. The -295 T-to-C polymorphism of the promoter region of the IL-16 gene was studied in 90 patients with WD and 152 healthy controls. Levels of serum IL-16 protein were also tested. The frequency of the wild type T allele was significantly higher in patients with WD compared to the controls (155/180 vs. 235/304; p = 0.02 for the Chi(2) test), odds ratio 1.82 [95 % confidence interval (CI) 1.07-3.10]. The TT genotype was found in 65/90 patients with WD and 88/152 controls (p = 0.026). No relationship was found between serum levels of IL-16 and genotypes. Although the functional consequences of this genetic background on levels of IL-16 and on the course of the disease are still unknown, we found, for the first time, that the wild type T allele and the TT genotype of the -295 polymorphism are associated with WD.

Cytokine genetic profile in Whipple's disease.

Whipple's disease (WD) is a very rare chronic systemic condition characterised by a Th2/T regulatory (Treg) dysregulated immune response versus Tropheryma whipplei, a bacterium widely diffuse in the environment. To investigate whether this Th2/Treg polarised response has a genetic background, we investigated the Th1, Th2, Th17 and Treg cytokine genetic profile of 133 patients with WD. Thanks to the European Consortium on WD (QLG1-CT-2002-01049), the polymorphism of 13 cytokine genes was analysed in 111 German and 22 Italian patients using the polymerase chain reaction with sequence-specific primers (PCR-SSP) technique. The frequencies of the genotypes, haplotypes and functional phenotypes were compared with those obtained in 201 German and 140 Italian controls. Clinical heterogeneity was also considered. Functionally, WD patients may be considered as low producers of TGF-ß1, having an increased frequency of the genotype TGF-ß1+869C/C,+915C/C [12.3 % vs. 3.81 %, odds ratio (OR) = 4.131, p = 0.0002] and high secretors of IL-4, carrying the genotype IL-4-590T/T (5.34 % vs. 1.17 %, OR = 5.09, p = 0.0096). No significant association was found between cytokine polymorphism and clinical variability. Analogously to the recent cellular findings of a Th2/Treg polarised response, we showed that the cytokine genetic profile of WD patients is skewed toward a Th2 and Treg response. This was similar in both German and Italian populations. However, the significant deviations versus the controls are poorer than that expected on the basis of these recent cellular findings.

Evidence for the presence of xenopsin-related peptide(s) in the gastric mucosa of mammals.

Using immunohistochemistry and radioimmunoassay, substance(s) related to the amphibian octapeptide xenopsin (XP) were demonstrated in the gastric mucosa of humans and dogs. Immunohistochemistry localized XP-immunoreactive epithelial cells in the gastric antral mucosa. The reaction was abolished by preabsorption of the antiserum with XP but not by neurotensin or other peptides. Immunoreactive XP (iXP) was found by radioimmunoassay in extracts of both the antrum and body of the stomach prepared with acid/acetone or acetic acid. A study of its distribution in the dog indicated that the level of iXP was highest in the stomach, lower in the pancreas and duodenum, and not measurable in the jejunoileum and colon. Gel chromatography on Sephadex G-25 indicated the presence of at least two forms of iXP, one larger and the other about the same size as XP. Reverse-phase high pressure liquid chromatography on mu-Bondapak C-18 yielded several peaks of iXP, one of which eluted at the position of synthetic XP. The results of immunochemical analyses using four different antisera towards XP were consistent with structures for canine iXPs that were closely related to XP only in their C-terminal regions. These results suggest that mammalian counterparts to amphibian XP reside within endocrine cells of the gastric mucosa. It seems possible that these peptides function as gastrointestinal signals.

Amphibian neurotensin (NT) is not xenopsin (XP): dual presence of NT-like and XP-like peptides in various amphibia.

To clarify whether xenopsin (XP) is the amphibian counterpart of mammalian neurotensin (NT), extracts of skin, brain, and intestine from representative amphibians were subjected to immunochemical, chromatographic, and biological analyses. The results indicated the dual presence of NT- and XP-like peptides in extracts of tissues from Xenopus laevis, Rana catesbeiana, Rana pipiens, Bufo marinus, Bufo americanus, and Necturus maculosus, which were separated during gel chromatography on Sephadex G-25 and high pressure liquid chromatography on mu-Bondapak C-18. Immunochemical studies, employing three different region-specific antisera toward NT (ox and man) and one antiserum towards XP (Xenopus laevis), indicated that the NT-like peptides shared COOH-terminal homologies with NT and differed at their NH2-termini. TWo classes of NT-like peptides could be distinguished on the basis of their distributions in tissues and their cross-reactivities with the antisera; immunoreactive NT measured using antiserum HC-8 tended to be found primarily in brain and intestine, whereas that reactive with antiserum PGL-4 was most concentrated in stomach, liver, and pancreas. Although also present in brain and intestine, immunoreactive XP was highest in stomach, pancreas, and skin. Partially purified immunoreactive NT and XP obtained from gastrointestinal tissues of Xenopus laevis and Bufo marinus were shown to increase the hematocrit and induce cyanosis in anesthesized rats. These findings indicate the presence of both NT- and XP-like peptides in neural and gastrointestinal tissues from several amphibia and suggest the possibility that XP-like peptides (apart from NT) may exist in other animals.

Presence of neurotensin and neuromedin-N within a common precursor from a human pancreatic neuroendocrine tumor.

An acid extract of a human neuroendocrine pancreatic adenoma was found to contain very high concentrations of immunoreactive neurotensin (iNT; approximately 130 mumol/L) as well as immunoreactive neuromedin-N (iNMN; approximately 40 mumol/L), portions of which (iNT, 0.2%; iNMN, 30%) were found in large molecular forms. Processing of the large forms could be mimicked by treatment with pepsin, which increased their immunoreactivity 15- to 20-fold (iNT) and 1- to 2-fold (iNMN), liberating a peptide similar to NMN and 2 fragments of NT [primary product, NT-(4-13)]. Biochemical characterizations using gel electrophoresis, isoelectric focusing, and high pressure liquid chromatography indicated that the large forms were highly basic (pI 8.5-9.5) proteins with a mol wt of about 20K (78% of the total), 45K (8%), and 60K (4%). The 20K protein contained iNT and iNMN in a 1:1 ratio, while a slightly smaller species contained only NMN. These results are in agreement with cDNA studies of canine intestinal mRNA, indicating the presence of a 170-amino acid precursor containing 1 copy each of NT and NMN. They further indicate that within this tumor differential processing of precursor occurred, resulting in a NT to NMN ratio of about 3:1, with additional NMN stored in large molecular forms.

Localization of xenin-immunoreactive cells in the duodenal mucosa of humans and various mammals.

Xenin is a 25-amino-acid peptide extractable from mammalian tissue. This peptide is biologically active. It stimulates exocrine pancreatic secretion and intestinal motility and inhibits gastric secretion of acid and food intake. Xenin circulates in the human plasma after meals. In this study, the cellular origin of xenin in the gastro-entero-pancreatic system of humans, Rhesus monkeys, and dogs was investigated by immunohistochemistry and immunoelectron microscopy. Sequence-specific antibodies against xenin detected specific endocrine cells in the duodenal and jejunal mucosa of all three species. These xenin-immunoreactive cells were distinct from enterochromaffin, somatostatin, motilin, cholecystokinin, neurotensin, and secretin cells, and comprised 8.8% of the chromogranin A-positive cells in the dog duodenum and 4.6% of the chromogranin A-positive cells in human duodenum. In all three species, co-localization of xenin was found with a subpopulation of gastric inhibitory polypeptide (GIP)-immunoreactive cells. Immunoelectron microscopy in the canine duodenal mucosa demonstrated accumulation of gold particles in round, homogeneous, and osmiophilic secretory granules with a closely adhering membrane of 187 +/- 19 nm diameter (mean +/- SEM). This cell type was found to be identical to the previously described canine GIP cell. Immunocytochemical expression of the peptide xenin in a subpopulation of chromogranin A-positive cells as well as the localization of xenin immunoreactivity in ultrastructurally characterized secretory granules permitted the identification of a novel endocrine cell type as the cellular source of circulating xenin.

Loss of predictive value of gastric ulcer symptoms in a randomized treatment trial.

Analysis of clinical data obtained in a double-blind randomized study, which compared liquid antacid (neutralizing capacity 120 mmol per day) with 1 g cimetidine in the treatment of 125 patients with gastric ulcer, revealed that, before starting treatment, 71% of the patients complained of epigastric pain, approximately 50% of bloating, and approximately 30% of nausea, heartburn, constipation or vomiting. Epigastric pain before treatment was significantly more frequent in patients with large ulcers (P less than 0.05) and in patients with ulcers unhealed after 4 weeks of therapy (P less than 0.05). This finding was the result of a highly significant correlation between diurnal epigastric pain and ulcer size and delayed healing (P less than 0.005). Nocturnal pain did not correlate with prognosis. In contrast to this correlation between pain before therapy and healing, the disappearance of epigastric pain with therapy did not signify ulcer healing. Only 14 (38%) of the 37 patients with healed ulcer were free from pain after the 4 weeks of therapy, whereas 25 (49%) of the 52 patients with persistent ulcers had no pain at this time. Placebo pain tablets relieved ulcer pain effectively in more than 85% of the patients, irrespective of whether the ulcer was healing or not. The other symptoms (bloating, nausea, heartburn, constipation or vomiting) were also alleviated by 4 weeks of therapy but no correlation was found with ulcer size or prognosis. The loss of the prognostic significance of ulcer pain is probably due to a complex interaction of the trial schedule on the patient's level of consciousness.(ABSTRACT TRUNCATED AT 250 WORDS)

Xenin--a review.

Xenin, a 25 amino acid peptide, has been identified in human gastric mucosa in the search for a counterpart to the amphibian octapeptide xenopsin. Xenin is structurally related also to the hypothalamic and ileal peptide neurotensin and is, therefore, a member of the xenopsin/neurotensin/xenin peptide family. The biological activities of these peptides are similar: Xenin has been shown to inhibit pentagastrin-stimulated secretion of acid, to induce exocrine pancreatic secretion and to affect small and large intestinal motility. In the gut, xenin interacts with the neurotensin receptor. Radioimmunoassay and chromatography of postprandial plasma in humans indicate the release of xenin into the circulation. The identification of a 35-amino acid precursor peptide of xenin - proxenin, and a review of the Gen-bank revealed that xenin represents the N terminus of a cytosolic coat protein (alpha-COP) from which xenin can be cleaved by aspartic proteinases such as pepsin and cathepsin E. The physiological role of the peptide xenin is not known.

Identification of proxenin as a precursor of the peptide xenin with sequence homology to yeast and mammalian coat protein alpha.

Proxenin a precursor of the bioactive peptide xenin, was isolated from canine pancreas by HPLC and identified by mass spectrometry and sequence analysis as a pentatriacontapeptide with a molecular weight of 4035: Met Leu-Thr Lys-Phe-Glu-Thr-Lys-Ser-Ala-Arg-Val-Lys-Gly-Leu-Ser- Phe-His-Pro-Lys-Arg-Pro-Trp.Ile-Leu-Thr-Ser-Leu-His-Asn-Gly-Val-Ile-Glo- Leu-OH. Treatment with pepsin cleaved off 10 C-terminal amino acids and released xenin. Data base search showed amino acid sequence homology of xenin and proxenin with the sequence of coal protein alpha of yeast (62%) and humans (100%). Concentration of the coatomer complex from rabbit liver led to an equimolar enrichment of extractable proxenin. We conclude, therefore, that xenin and proxenin are peptide sequences highly conserved during evolution within the alpha-subunit of the coatomer.