[The role of small bowel microflora in the development of secondary lactase deficiency and the possibilities of its treatment with probiotics].

AIM: To estimate the incidence of secondary lactase deficiency (SLD) in patients with postinfectious irritable bowel syndrome (PIBS) and the value of the small bowel microflora in its development and to elaborate treatment options for SLD. SUBJECTS AND METHODS: One hundred and thirty-eight patients with PIBS, including 112 (81.2%) women and 26 (18.8%) men, were examined. The patients' mean age was 33.9 +/- 9.1 years. The duration of the disease was 2.6 +/- 1.4 years. Lactase deficiency (LD) was diagnosed using the color scale to test biopsy specimens from the duodenal retrobulbar region. The bacterial overgrowth syndrome (BOS) was identified by a 2-hour lactulose (20 ml) hydrogen breath test. Sixty patients with moderate SLD were randomized to 2 groups: 1) 41 patients received basic therapy (mesim forte as one tablet t.i.d., no-spa, 40 mg, t.i.d.) and combined probiotic bifiform (Ferrosan) containing Bifidobacterium longum 107, Enterococcus faecium 107 as one capsule t.i.d. for 14 days. Group 2 patients (n = 19) had basic therapy in combination with placebo. RESULTS: SLD was detected in 59.4% of the patients with PIBS, including 43.5 and 15.9% with moderate and severe forms, respectively. In all cases, SLD was accompanied by BOS in the small bowel lumen, as confirmed by the results of a hydrogen breath test [101 +/- 37 ppm (a normal value of < 20 ppm)]. After a 14-day course of therapy with the combined probiotic bifiform, restoration of eubiosis in the small bowel lumen was achieved in 70.8% of the patients, as shown by the lesser degree of BOS (86.9 +/- 40.9 and 17.4 +/- 6.6 ppm before and after treatment, respectively; p < 0.01) and by normalization of the lactase test (p < 0.01). In the comparative placebo group, 68.4% showed no clear positive changes, SLD and BOS remained. CONCLUSION: The changes in the small bowel intraluminal microflora, which developed after prior intestinal infection, played a great role in the development of SLD. Bifiform belongs to the currently available probiotics and may be recommended to correct SLD in patients with PIBS resulting from the impaired microbiota of the small bowel and to prevent BOS.

Adaptative response of alpha- and beta-glucosidase kinetics along the villi of rat self-filling jejunal blind loops.

Four and 12 days after the construction of self-filling jejunal blind loops in the rat, the apparent Km- and Vmax-values of lactase/beta-glucosidase and neutral alpha-glucosidase were determined by in-situ quantitative enzyme histochemistry, and changes in the villus-crypt architecture of the mucosa were examined by microdissection. The results were compared with corresponding data from sham-operated controls. The kinetics data were obtained from the base and the transition zone between medium and apical villus third by the use of a microdensitometric technique. The apparent Vmax of lactase/beta-glucosidase is significantly smaller than in the control rats at both measuring sites of the villi and even decreases from day 4 to day 12. The apparent Vmax of neural alpha-glucosidase is not affected, and thus the same increase in enzyme activity along the villi as in the controls is observed. The apparent Km of this enzyme, however, is already significantly increased on day 4 at both villus positions in the blind loops. A pronounced increase in villus surface area is detected in the blind loops as a result of an increase in crypt cell proliferation. The results indicate that enzymatic adaptation in the self-filling blind loops of rat jejunum exhibits different patterns for brush border alpha- and beta-glucosidases and is at least in part accomplished independently of the pronounced mucosal transformation occurring in this experimental condition.

Pathogenesis of mucosal injury in the blind loop syndrome.

Bacterial extracts were prepared from cultures originating in chronic self-filling intestinal blind loops in rats. Their ability to remove active maltase molecules from isolated brush border membranes was studied in vitro. Twelve strains in 51 tested, belonging to one of three species, Bacteroides fragilis, Clostridium perfringens, and Streptococcus fecalis, possessed maltase-releasing activity. The ability to remove maltase correlated well with the ability to hydrolyze p-nitrophenyl-tert-butyloxycarbonyl-l-alaninate (NBA), an ester substrate rapidly hydrolyzed by elastase, but not with substrated favored by tryhsin and chymotrypsin. Maltase-releasing activity from C. perfringens was strongly inhibited by soybean trypsin inhibitor and to a lesser extent by lima bean trypsin inhibitor. Of four chloromethylketone active-site directed inhibitors tested with specificities for elastase, trypsin, and chymotrypsin, inhibition was maximal with elastase-specific inhibitors. In two species, activity was shown to be heat sensitive, and to be inhibited by concentration of the extract. In one species maltase-releasing activity was shown to be due to an enzyme of molecular weight at least 66,000 with the capacity to remove lactase, sucrase, and alkaline phosphatase, as well as maltase. The results indicate that anaerobic or facultatively anaerobic species, previously identified with the pathology of of the blind loop syndrome, contain proteases which are capable of removing components of the intestinal surface membrane. These proteases appear to have elastase-like substrate specificity and may be involved in the etiology of disaccharidase deficiency in bacterial overgrowth syndromes.

Pathogenesis of mucosal injury in the blind loop syndrome. Brush border enzyme activity and glycoprotein degradation.

The effect of intestinal bacterial over-growth on brush border hydrolases and brush border glycoproteins was studied in nonoperated control rats, control rats with surgically introduced jejunal self-emptying blind loops, and rats with surgically introduced jejunal self-filling blind loops. Data were analyzed from blind loop segments, segments above and below the blind loops, and three corresponding segments in the nonoperated controls. Rats with self-filling blind loops had significantly greater fat excretion than controls and exhibited significantly lower conjugated:free bile salt ratios in all three segments. Maltase, sucrase, and lactase activities were significantly reduced in homogenates and isolated brush borders from the self-filling blind loop, but alkaline phosphatase was not affected. The relative degradation rate of homogenate and brush border glycoproteins was assessed by a double-isotope technique involving the injection of d-[6-(3)H]glucosamine 3 h and d-[U-(14)C]glucosamine 19 h before sacrifice, and recorded as a (3)H:(14)C ratio. The relative degradation rate in both homogenate and brush border fractions was significantly greater in most segments from rats with self-filling blind loops. In the upper and blind loop segments from rats with self-filling blind loops, the (3)H:(14)C ratios were higher in the brush border membrane than in the corresponding homogenates, indicating that the increased rates of degradation primarily involve membrane glycoproteins. Incorporation of d-[6-(3)H]glucosamine by brush border glycoproteins was not reduced in rats with self-filling blind loops, suggesting that glycoprotein synthesis was not affected. Polyacrylamide gel electrophoresis of brush border glycoproteins from the contaminated segments indicated that the large molecular weight glycoproteins, which include many of the surface hydrolases, were degraded most rapidly. Brush border maltase, isolated by immunoprecipitation, had (3)H:(14)C ratios characteristic of the most rapidly degraded glycoproteins. The results indicate that bacteria enhance the destruction of intestinal surface glycoproteins including disaccharidases. Since alkaline phosphatase, a glycoprotein, is not affected, the destruction is selective and presumably involves only the most exposed membrane components.

Brush border peptidases and arylamidases in the experimental blind loop syndrome of the rat.

Peptidase and arylamidase activities were assessed in purified brush borders from jejunum of rats with surgically created blind loops. The blind loop segment and the jejunum proximal and distal to the blind loop were studied. Comparable jejunal segments from control rats were also studied. The blind loop syndrome was documented by presence of macrocytic anemia. Enzyme activities were determined on purified brush borders. In rats with the blind loop syndromes enzymatic activities hydrolizing sucrose, L-Leucyl-beta-naphthylamide, L-lysyl-beta-naphthylamide, alpha-L-glutamyl-beta-naphthylamide, L-phenylalanyl-alanine and L-leucyl-glycine were significantly reduced as compared to controls (P less than 0.001). After a short course of antibiotic therapy enzymatic activities returned to normal. Our findings suggest a reversible intestinal mucosa damage in the rat with blind loop syndrome.

Effect of stasis on intestinal enzyme activities.

Activities of the small intestinal mucosal enzymes lactase, sucrase, maltase, alkaline phosphatase and N-acetyl-beta-glucosaminidase were studied in rats with surgically-induced upper intestinal stasis and in control animals. The first four are brush border enzymes, the latter a lysosomal enzyme. There was a reduction in the activities of all enzymes in the operated animals. The change lining was significant and most marked in mucosa the blind loop and gut distal to it; areas in which there is gross bacterial overgrowth and excessive levels of intraluminal deconjugated bile salts. The significance of these findings in relation to malabsorption consequent on bacterial contamination of the upper gut is uncertain and requires further study.