Control of acute, chronic, and constitutive hyperammonemia by wild-type and genetically engineered Lactobacillus plantarum in rodents

Abstract

Hyperammonemia is a common complication of acute and chronic liver diseases. Often accompanied with side effects, therapeutic interventions such as antibiotics or lactulose are generally targeted to decrease the intestinal production and absorption of ammonia. In this study, we aimed to modulate hyperammonemia in three rodent models by administration of wild-type Lactobacillus plantarum, a genetically engineered ammonia hyperconsuming strain, and a strain deficient for the ammonia transporter. Wild-type and metabolically engineered L. plantarum strains were administered in ornithine transcarbamoylase-deficient Sparse-fur mice, a model of constitutive hyperammonemia, in a carbon tetrachloride rat model of chronic liver insufficiency and in a thioacetamide-induced acute liver failure mice model. Constitutive hyperammonemia in Sparse-fur mice and hyperammonemia in a rat model of chronic hepatic insufficiency were efficiently decreased by Lactobacillus administration. In a murine thioacetamide-induced model of acute liver failure, administration of probiotics significantly increased survival and decreased blood and fecal ammonia. The ammonia hyperconsuming strain exhibited a beneficial effect at a lower dose than its wild-type counterpart. Improved survival in the acute liver failure mice model was associated with lower blood ammonia levels but also with a decrease of astrocyte swelling in the brain cortex. Modulation of ammonia was abolished after administration of the strain deficient in the ammonium transporter. Intestinal pH was clearly lowered for all strains and no changes in gut flora were observed. Conclusion: Hyperammonemia in constitutive model or after acute or chronic induced liver failure can be controlled by the administration of L. plantarum with a significant effect on survival. The mechanism involved in this ammonia decrease implicates direct ammonia consumption in the gut. (HEPATOLOGY 2008;48:1184-1192 H yperammonemia (HA) is a well-known complication of acute and chronic liver diseases and plays a central role in the pathogenesis of hepatic encephalopathy (HE). [1][2][3][4][5] This neurological dysfunction results, at least in part, from an increase in plasma ammonia level and the severity of the symptoms correlates with blood ammonia level. 6-9 Animal models used in studying hyperammonemic disorders are multiple: fulminant hepatic failure, 10 chronic liver failure, 11 or urea cycle deficiency. 12 Ammonia is produced by many tissues but its major external source results from deaminase and urease activities of the gut flora. Although its absorption occurs through the intestinal epithelium, ammonia is carried by the portal vein into the liver where it is metabolized into urea. 13 Classical treatments of HE, except through liver transplantation and liver replacement therapies, consist in decreasing the ammonia production of urease-positive bacteria by antibiotics or decreasing the ammonia absorption into the gut by acidifying the colon content with nonabsorbable sugars such as lactulose. 4,[13][14][1...

Ammonia Mediates Methamphetamine-Induced Increases in Glutamate and Excitotoxicity

“…This dosing paradigm models the concentration and binge paradigm reported in METH-dependent humans and produces longterm depletions of dopamine and serotonin terminals (Cruickshank and Dyer, 2009;McCann et al, 1998;McKetin et al, 2006;Ricaurte et al, 1982;Wagner et al, 1980). Peripheral ammonia excretion was increased using lactulose, as it is a well-known treatment that enhances ammonia excretion and attenuates the increases in plasma ammonia and neurological symptoms of hepatic encephalopathy (Al Sibae and McGuire, 2009;Jia and Zhang, 2005;Nicaise et al, 2008). In lactulose experiments, rats received lactulose (5.3 g/kg) or vehicle via oral gavage every 12 h for 2 days before METH treatment until the day before rats were killed (Halpin and Yamamoto, 2012).…”

“…It is hypothesized that ammonia increases extracellular striatal glutamate through an alteration in glutamate transporter function, the result of which is calpain-mediated spectrin proteolysis indicative of calciumdependent excitotoxicity (Siman et al, 1989). To evaluate the role of ammonia, we used the non-absorbable disaccharide lactulose, which is a primary treatment for hepatic encephalopathy and is used to lower elevated plasma ammonia resulting from hepatotoxicity (Al Sibae and McGuire, 2009;Jia and Zhang, 2005;Nicaise et al, 2008). Subsequent to oral administration, lactulose remains in the gut and increases the fecal excretion of ammonia through numerous mechanisms including acidifying the intestinal lumen to trap enterohepatically cycling NH 4 þ , functioning as a laxative to increase intestinal motility and decrease protein absorption, which is the sole dietary source of ammonia, and through increasing ammonia metabolism by intestinal bacteria (Mortensen, 1992;Panesar and Kumari, 2011).…”

Ingestion of Lactobacillus strain reduces anxiety and improves cognitive function in the hyperammonemia rat

“…These treatments, however, are not optimal therapies because of their side effects, toxicities, and poor compliance from patients [22]. Probiotics, such as the Lactobacillus species, are living microorganisms that contribute to the balance of intestinal microbiota, thereby improving the health of the host.…”

346 Engineering the Gut Microbiota to Treat Hyperammonemia

“…Nevertheless, the reduction in fecal ammonia levels compared with those at baseline remained significant for several months, even in mice on a nonirradiated diet ( Figure 5D). Reductions in fecal ammonia levels have been correlated with reductions in blood ammonia (14,27,28), indicating that changes in colonic ammonia production and/or absorption can be associated with blood levels. The reduction in fecal ammonia may alter levels of false neurotransmitter precursors produced by the gut microbiota and/or by the host, since ammonia is a substrate for both, and this would lead to reduced formation of the biogenic amines that are hypothesized to play a role in HE (29)(30)(31).…”

“…Lactulose is used to acidify feces and sequester ammonia as ammonium, but lactulose is poorly tolerated, resulting in poor adherence (13). In a mouse model of thioacetamide-induced liver injury, a lactobacillus probiotic has been reported to reduce ammonia levels and mortality (14), but these benefits have not been extended to human studies (15,16). While promising, studies of probiotic therapies in humans described to date have suffered from methodological limitations, did not document long-term effects, and showed consistently minimal effects on outcome, motivating efforts to engineer more resilient and effective bacterial communities.…”