A New Factor from Enteric Bacteria of Rats Amplifying Induction of Liver Enzyme by Glucocorticoid. 1. Purification, Properties and Biological Action

Abstract

1. A factor, which amplifies the inductions of several liver enzymes by glucocorticoid, was partially purified from Proteus mirabilis from rat intestine. The factor (amplifier) was completely inactivated by ct-glucosidase, but not by other glycoside hydrolases, proteases, nucleases or phosphatases tested; it was also hydrolysed by HCI with liberation of reducing sugars. Thus the oligosaccharide in this factor seems to be essential for the amplification.2. In adrenalectomized rats the amplifier increased the inductions of several liver enzymes, such as tyrosine aminotransferase and leucine aminotransferase, by glucocorticoid. But it did not amplify the induction of tyrosine aminotransferase by glucagon or insulin or the activities of enzymes that are not induced by glucocorticoid. The amplifier by itself did not have any glucocorticoid-like action in adrenalectomized rat. These results show that the amplifier specifically increases the inductions of liver enzymes by glucocorticoid.3. Since a similar amplification was also observed in isolated perfused liver and cultured hepatoma cells in vitro, the amplifier seems to act directly on the target organ or cells.Previously we found that administration of a small dose of glucocorticoid induced less liver tyrosine aminotransferase in germ-free rats than in normal rats. This suggested that intestinal flora increased the action of glucocorticoid.Therefore, we examined the actions of fractions of enteric bacteria on the induction of liver enzymes by glucocorticoid. We isolated a fraction that amplified the inductions of several liver enzymes by glucocorticoid: it had a direct action on the liver or cells in the presence of glucocorticoid, but none in the absence of glucocorticoid. Fractions with amplifying actions were obtained from several enteric bacteria, such as Proteus mirabilis, Laclobacillus and Streptococcus, but not Saccharomyces; the fraction from P. mirahilis had the most activity. The factor purified from P. mirahilis is effective at very low concentration,

Effect of intestinal flora on the metabolism of amino acids and proteins in mouse.

“…As there was no difference in the leucine pool in livers among germ-free, con ventionalized and conventional mice (Table 1), these results indicate that the utilization of amino acids (the incorporation of amino acids into liver-soluble protein) was increased in the host liver by some action of intestinal flora. This increase in the synthesis of liver protein probably was not due to the cortisone amplifying factor produced by intestinal flora (11,12), which is believed to induce only certain specific liver proteins but not total liver protein. Further studies are needed to define the mechanism by which intestinal flora increase protein synthesis in the liver of host animals.…”

“…For some decades, many studies have been made on the influence of non-pathogenic flora on morphological and biological changes of intestinal mucosa (4,5), intestinal peristalysis (6), the accumulation of nitrogen (7) and the amount of amino acids in the intestines of host animals (8-10). Recently, it was found that some compounds produced by intestinal flora amplify the cortisone effects including enzyme induction (11,12). This finding suggested the participation of intestinal flora in the regulation of metabolism in the host animal.…”

The differences of the metabolism related to vitamin B6-dependent enzymes among vitamin B6-deficient germ-free and conventional rats.

“…It has also been reported that the presence of intestinal microflora may contribute something to the improvement of vitamin B6-deficiency in animals (6)(7)(8). Recently, KATUNUMA et al showed that intestinal microflora synthesized a new factor which enhanced several actions of glucocorticoid (9), and glucocorticoid was an inducer of aminotransferases of alanine, aspartate and tyrosine (10,11). These reports suggest that the activities of vitamin B6-dependent enzymes in conventional rats may differ from those in germ-free rats which retain no intestinal microflora.…”

“…There were considerable decreases in aspartate aminotransferase activities from erythrocytes and in alanine aminotransferase activities from liver between conventional control and germ-free control rats. Since it has been reported that a factor enhancing glucocorticoid actions was synthesized by intestinal microflora in animals (9), and glucocorticoid induced alanine and aspartate aminotransferases in liver (10,11), the considerably high activities of their enzymes in conventional control rats might indicate the effect of the factor synthesized by intestinal microflora in conventional rats.…”

Tumor-promoting phorbol ester amplifies the inductions of tyrosine aminotransferase and ornithine decarboxylase by glucocorticoid

“…Recently the findings that many compounds, such as interferon, muramyl dipeptide, thymosin ab and various lymphokines, modulate immunological responses have led to the concept of "biological responses modulators" (Ivarie & O '-Farrell, 1978). In the case of hormonal responses, we have long proposed the existence of modulators that specifically enhance the actions of glucocorticoids in target organs or cells (Katunuma et al, 1971(Katunuma et al, , 1977Kido et al, 1977), and these modulators have recently been summarized and termed "glucocorticoid action biomodulators" (Kido et al, 1986).…”