Charles Dive

Stimulation of secretory IgA and secretory component of immunoglobulins in small intestine of rats treated with Saccharomyces boulardii.

Saccharomyces boulardii (S.b.) is largely used in Western European countries for the treatment of acute infectious enteritis and antibiotic-induced gastrointestinal disorders. To study the mechanisms of the protective effect of S.b. against enteral pathogen infection, we assessed the response of the intestinal secretion of secretory IgA (s-IgA) and of the secretory component of immunoglobulins (SC) to oral administration of high doses (0.5 mg/g body weight, three times per day) of S.b. cells in growing rats. S.b. cells (biological activity: 2.8× 109 viable cells/100 mg) were administered daily by gastric intubation to weanling rats from day 14 until day 22 postpartum. Control groups received either 0.9% saline or ovalbumin following the same schedule. Expressed per milligram of cell protein, SC content was significantly increased in crypt cells isolated from the jejunum (48.5% vs saline controls, P< 0.05) as it was in the duodenal fluid (62.8% vs saline controls, P<0.01) of rats treated with S.b. Oral treatment with S.b. had no effect on the secretion of SC by the liver. In the duodenal fluid of rats treated with S.b. cells, the mean concentration of s-IgA was increased by 56.9% (P<0.01) over the concentration of s-IgA measured in saline controls. Compared to control rats treated from day 14 until day 22 postpartum with an antigenic load of ovalbumin equivalent to the total protein load provided by Sb cells (0.05 mg protein/g body weight, three times per day), S.b.-treated rats also exhibited a significantly higher intestinal concentration of SC (69% in villus cells, P<0.025 and 80% in crypt cells, P<0.01 These changes in intestinal SC and s-IgA concentration appeared not to be due to an increase in enterocyte turnover rate, since the mucosal mass parameters and the incorporation rate of [3H]thymidine into DNA measured in the jejunum, ileum, and colon remained unchanged in S.b.- treated rats. Our findings suggest that one of the mechanisms by which S.b. exerts its immunoprotective effect in the gastrointestinal tract is a stimulation of the intestinal secretion of s-IgA and of the secretory component of immunoglobulins.

Selective Transport of Polymeric Immunoglobulin-a in Bile - Quantitative Relationships of Monomeric and Polymeric Immunoglobulin-a, Immunoglobulin-m, and Other Proteins in Serum, Bile, and Saliva

In 17 adults, serum, hepatic bile, and saliva samples were analyzed for their sedimentation profile of IgA and secretory component (SC), and for their concentrations of albumin, orosomucoid, transferrin, IgG, IgA, alpha 2-macroglobulin (alpha 2M), IgM, and SC. Polymeric IgA(p-IgA) averaged 13% (50-700 micrograms/ml) of total IgA in serum, 70% (43-88%) in bile, and 93% (74-98%) in saliva. Most of the p-IgA in bile sedimented with SC, which also occurred free (8-44%), and with IgM. In bile, albumin (155-1,485 micrograms/ml) was the predominant protein, followed by IgG (32-480 micrograms/ml), and total IgA (37-209 micrograms/ml). In saliva, p-IgA (72-902 micrograms/ml) predominated, followed by albumin (16-385 micrograms/ml) and IgG (9-178 micrograms/ml). Secretion-to-serum albumin-relative concentration ratios (S/S-ARCR = 1 for albumin) in bile averaged 22 for p-IgA, 1.91 for IgM, 1.28 for monomeric IgA (m-IgA), 0.70 for IgG, and 0.57 for alpha 2M, indicating for p-IgA, IgM, and to a lesser extent for m-IgA, a selective excretion into bile. In saliva, a 16-fold greater selective excretion of p-IgA (mean S/S-ARCR = 354) was found. Labeled m- and p-IgA were injected intravenously into five patients. Specific activities indicated that for p-IgA 50% was serum derived in bile, as compared with 2% in saliva, and to 85% for m-IgA in bile. In the patient with the highest excretion of 125I-p-IgA in bile, only 2.8% of the injected dose was recovered in bile within 24 h after injection. Compared with rats and rabbits, the serum-to-bile transport of p-IgA in humans is much smaller.

Changes in size, subclass, and metabolic properties of serum immunoglobulin A in liver diseases and in other diseases with high serum immunoglobulin A.

We have studied the relative contributions of monomeric (m-) and polymeric IgA (p-IgA) and of IgA1 and IgA2 to total serum IgA in healthy adults and patients with liver disease (LD) or with other diseases and high serum IgA. Serum concentration of total secretory component (SC) was also determined. In addition, fractional catabolic rates (FCR) and synthetic rates for both m- and p-IgA were measured in nine controls and nine cirrhotics. Our results support four main conclusions: (a) In healthy adults, intravascular p-IgA contributes to only 4-22% (mean 12%) of serum IgA, because its FCR and synthetic rate are approximately two times higher and four times smaller, respectively, than those of intravascular m-IgA. (b) in LD, biliary obstruction does not result in a significant increase in serum p-IgA unlike in rats and rabbits, indicating that in humans the SC-dependent biliary transport of p-IgA plays a much less significant role in selective removal of p-IgA from plasma than in rats and rabbits. (c) In contrast to biliary obstruction, parenchymal LD results in a significant and preferential increase in serum p-IgA, which in cirrhotics correlates with a selective reduction of the p-IgA-FCR. This supports a role for the human liver in selective removal of p-IgA from plasma, but another mechanism than the SC-dependent biliary transport should be considered. (d) Total SC, p-IgA, and IgA2 in serum are unlinked parameters, not necessarily reflecting mucosal events. A marked increase in serum SC occurs almost selectively in LD. Although a shift to IgA2 is suggested in Crohns disease and alcoholic cirrhosis, a shift to IgA1 frequently associated to a shift to p-IgA occurs in chronic active LD, primary Sicca, and connective tissue diseases.

Secretion of immunoglobulins and plasma proteins from the jejunal mucosa. Transport rate and origin of polymeric immunoglobulin A.

Parameters of secretion of IgA and several other plasma proteins from the jejunal mucosa were investigated in 11 individuals who had a normal distribution of Ig-containing cells in the lamina propria and in one patient who was totally deficient in jejunal IgA and IgM plasmacytes. Jejunal samples were collected during segmental gut perfusion. The following results were obtained: (a) The secretion of polymeric IgA (p-IgA, mean equals 217 micrograms/40 cm per min) exceeded those of albumin (132 micrograms), IgG (35 micrograms), and monomeric IgA (m-IgA, 15 micrograms, or 6.4% of total IgA). About 35% of IgA was IgA2 in the jejunal secretion, compared with approximately 23% in serum. This closely corresponds to the 35 and 24% of IgA2 plasmocytes in jejunal mucosa and peripheral lymph nodes, respectively. (b) For each protein, a relative coefficient of excretion (RCE) was calculated (jejunum to serum concentration ratio expressed relative to that of albumin). RCEs of 1.41 for orosomucoid, 1.0 for albumin, 0.83 for IgG, and 0.74 for IgE and, in the deficient patient, of 0.64 for m-IgA and 0.016 for IgM were obtained. This was inversely related to the molecular weight of these proteins and indicated their predominantly passive transport into the jejunum. However, in normal individuals, the RCE of transferrin (approximately 1.11 greater than 1, P greater than 0.05), alpha 2-macro globulin (approximately 0.77), m-IgA (approximately 1.98), and p-IgA (approximately 218) exceeded the value expected from simple seepage from plasma, thus pointing to an additional role of either local gut synthesis and/or active transepithelial transport. (c) Approximately 98% of p-IgA, approximately 99% of IgM, and approximately 68% of m-IgA in jejunal secretions were derived from local production in the gut wall, as determined by 125I-p-IgA specific activities and/or by comparison between the RCE values of the deficient patient to the values of controls. Therefore, the jejunal production of p-IgA (approximately 312 mg/d per 40 cm vs. approximately 54 mg/d from bile) contributes the majority of upper intestinal IgA in humans. The active transport of plasma p-IgA across the intestinal mucosa (approximately 0.08 mg/40 cm per kg per d) contributes less than 2% of the total amount of p-IgA (4.5 mg/kg per d) that is cleared daily from plasma.

Controlled Trial of Cimetidine in Reflux Esophagitis

In an eight-week double-blind trial, the effectiveness of cimetidine (1.6 g/day) was compared to placebo in 34 patients with symptomatic esophagitis confirmed by endoscopy with biopsies and/or by acid infusion test. Patients treated with cimetidine had significantly less symptomatic days during the first six weeks and less symptomatic nights during the first two weeks, and they consumed less antacids during the whole trial period. Endoscopic evaluation of 17 patients on cimetidine and of 15 patients on placebo did not show any significant difference in severity and extent of esophageal lesions after eight weeks, but histological assessment of 16 patients on cimetidine and 13 patients on placebo showed a significant improvement after eight weeks of cimetidine (P<0.025). These results show that cimetidine has a rapid effect on symptoms of reflux esophagitis and that, in some cases, it may reduce the esophageal lesions after eight weeks.

Dynamic CT in pancreatic lymphoma

We retrospectively reviewed the dynamic CT examinations of eight patients with pancreatic lymphoma. Four tumors were rounded masses with well-defined contours, four were more infiltrating lesions. The median cross-sectional diameter of the tumors was 6 cm (range 2.5–12 cm). At dynamic CT, the tumors were hypodense (n = 8) and somewhat heterogeneous (n = 6). Additional features were enlarged lymph nodes, 1–3 cm in diameter (n = 5), dilatation of the biliary tract and pancreatic duct (n = 5), abnormalities in the fat around the celiac trunk and/or the superior mesenteric artery (n = 4), and venous stenosis or occlusion (n = 7). The CT findings of pancreatic lymphoma are more various than has been previously reported. Findings such as small tumor size, well-defined contours, tumor heterogeneity, pancreatic duct dilatation, and venous invasion may be seen. Pancreatic lymphoma cannot be reliably distinguished from pancreatic carcinoma by CT findings alone.

Breath 14CO2 after intravenous administration of [14C]aminopyrine in liver diseases.

The determination of14CO2 in breath after oral administration of [14C]aminopyrine has been proposed as a quantitative liver function test. In order to shorten the procedure and avoid misinterpretations related to variable rates of intestinal absorption, the [14C]aminopyrine breath test (ABT) was performed after intravenous administration of [14C]aminopyrine in 21 controls and 89 patients with biopsy-proven liver disease. The specific activity of the first hour sample corrected for body weight (SA1) was the most discriminant expression of breath data. The SA1 value, expressed as the percentage of the administered dose, was 0.86±0.1% (mean±sd) in controls and significantly less in patients (0.46 ±0.31%). Low values were observed in patients with untreated chronic active hepatitis (0.16±0.13%), alcoholic cirrhosis (0.2±0.15%), and untreated postnecrotic cirrhosis (0.47±0.17%). In contrast, normal values were obtained in chronic persistent hepatitis (0.86±0.13%) and 58% of noncirrhotic alcoholic liver diseases (0.83±0.27%). The results of duplicate studies were reproducible and SA1 correlated with other conventional liver function tests, including 45-min BSP retention. Among these, ABT was the most sensitive screening test for the presence of cirrhosis, especially in alcoholic patients, where it allowed a sharp distinction between cirrhotic and noncirrhotic cases. The results obtained in chronic hepatitis suggested that ABT may provide a reliable index of the activity of the disease. In our hands, intravenous ABT, performed over a 1-hr period, was a fast, sensitive, and discriminant liver function test.

Intestinal development in the suckling rat: effect of insulin on the maturation of villus and crypt cell functions.

Abstract The influence of insulin on the postnatal development of intestinal functions linked to villus cells (sucrase, lactase, maltase and aminopeptidase) and crypt cells (secretory component of immunoglobulins, SC) has been studied in suckling and weanling rats. At 9 days of age, the animals received a daily injection of insulin 12·5 mU g‐1body weight day‐1for 4 days. Compared with saline‐treated controls, insulin had no effect on the development of the intestinal mucosal mass parameters determined in the jejunum, ileum and colon. A premature appearance of sucrase was noted in isolated jejunal villus and crypt cells, the level of activity reached by the enzyme being dependent of the amount of insulin injected. By 6 and 12 h after a single injection of the hormone (12·5 mU g‐1body weight), sucrase activity was detected in all the cell fractions along the villus‐crypt axis. In villus cells of insulin‐treated rats, maltase, lactase and aminopeptidase activities were significantly (P < 0·001) increased (+201%, +50%, +207%, respectively, vs. controls), whereas the concentration of SC measured by a sensitive immunoradiometric assay was enhanced over the controls by 75% in villus cells, 83% in crypt cells and 172% in the liver. Weanling rats treated from day 10 to day 20 postpartum with 12·5 mU insulin also exhibited a higher intestinal production of SC (+93%, P < 0·01) than did saline controls. The administration of Actinomycin D to 9‐day‐old suckling rats 1 h after insulin injection completely inhibited the adaptative process to the hormone; the activities of sucrase, lactase, maltase and aminopeptidase measured in rats treated with Actinomycin D being equivalent to those recorded in saline controls. Our data demonstrate that: (i) a premature increase of the circulating level of insulin accelerates the maturation of intestinal functions linked to both villus and crypt cells; (ii) the response to the hormone occurs rapidly over the entire villus‐crypt unit, whatever the degree of epithelial cellular differentiation; (iii) the stimulation of the synthesis of brushborder membrane enzymes by insulin appears to be regulated at the level of transcription.

Localization and serum concentration of secretory component during massive necrosis of human liver.

The serum concentration of secretory component was monitored in 9 patients with massive liver necrosis. During acute cytolysis, no increase in serum secretory component levels was observed. Later on, patients with fulminant evolution displayed minor elevations. Values as high as those usually found in acute hepatitis were only observed in cases with delayed liver failure. In these patients, levels were elevated before failure, dropped as liver failure developed, and rose again during recovery. This evolution of serum secretory component level cannot be accounted for by a defective liver clearance of circulating secretory component. It rather suggests a release into the blood of secretory component produced in the liver by cells other than damaged hepatocytes, possibly during liver regeneration. In 3 cases, secretory component localization in the liver was demonstrated by immunocytochemistry and was compared with that in normal liver and in obstructive jaundice. In normal liver, it was restricted to portal bile duct cells and lumens. In obstructive jaundice, additional secretory component staining was found in bile canaliculi. After fatal liver necrosis, secretory component was localized to portal ducts and to a variable proportion of the cholangiocytelike cells belonging to the numerous extraportal proliferating ducts. In these structures, 0.1%, 21%, and 4% of the cells were stained 3, 8, and 30 days after maximal cytolysis, respectively. Remaining hepatocytes and bile canaliculi or bile plugs were unstained. Therefore, portal cholangiocytes and extraportal cholangiocytelike cells are probably essential sources of secretory component in human liver. We propose that proliferation of extraportal cholangiocytelike cells, expression of secretory component synthesis by these cells, and their inability to secrete secretory component in a disorganized biliary tree result in the elevated serum concentration of secretory component observed after acute liver necrosis.

Refeeding after starvation in the rat: comparative effects of lipids, proteins and carbohydrates on jejunal and ileal mucosal adaptation.

Abstract. To compare the tropic effect of different dietary nutrients on mucosal adaptation in the jejunum and ileum, adult rats were submitted to a 96‐h period of starvation and refed isocaloric liquid diets (1.5 kcal ml‐1) containing either protein (casein), carbohydrate (starch) or lipids. In the jejunum, 4 days of starvation caused mucosal hypoplasia, villus and crypt shortening and a decrease in the total activity of disaccharidases with the exception of lactase which was markedly enhanced. In contrast, mucosal hypoplasia was incomplete in the ileum which exhibited an increase in crypt depth and in the specific and total activities of disaccharidases and of aminopeptidase.