Elental® amino acid component has protective effects on primary cultured hepatocytes and a rat model of acute liver injury

The role of amino acid metabolism in autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory chronic liver disease with persistent and recurrent immune-mediated liver injury. The exact cause of AIH is still not fully understood, but it is believed to be primarily due to an abnormal activation of the immune system, leading to autoimmune injury caused by the breakdown of autoimmune tolerance. Although the pathogenesis of AIH remains unclear, recent studies have shown that abnormalities in amino acid metabolism play significant roles in its development. These abnormalities in amino acid metabolism can lead to remodeling of metabolic processes, activation of signaling pathways, and immune responses, which may present new opportunities for clinical intervention in AIH. In this paper, we first briefly outline the recent progress of clinically relevant research on AIH, focusing on the role of specific amino acid metabolism (including glutamine, cysteine, tryptophan, branched-chain amino acids, etc.) and their associated metabolites, as well as related pathways, in the development of AIH. Furthermore, we discuss the scientific issues that remain to be resolved regarding amino acid metabolism, AIH development and related clinical interventions, with the aim of contributing to the future development of amino acid metabolism-based as a new target for the clinical diagnosis and treatment of AIH.

Detection of Decarboxylated Amino Acids after in Vitro Protease Digestion of the Hydrophilic Fraction of Crude Drug Extracts

Many constituents of crude drugs in Japanese Kampo formulas are thought to function as pro-drugs, whose pharmacological activity is manifested after oral administration. Proteins and peptides in crude drugs may be digested and metabolized in the digestive tract and liver. However, few studies have reported the pharmacological activity of peptides in crude drugs. Here, we applied an analysis using LC-tandem mass spectrometry (LC-MS/MS) to identify the compounds derived from six crude drugs that are assumed to have anti-inflammatory effects. To simulate in vivo protease digestion, each water-soluble fraction of the crude drug extracts was treated with proteases, including endoproteinases and exopeptidases. Amines in the resultant digests were modified by 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and analyzed using LC-MS/MS, which demonstrated the presence of four decarboxylated amino acids (primary amines). In the digest of the hydrophilic fraction of the fruit of Ziziphus jujuba Miller var. inermis Rehder (Taiso), isobutylamine, isoamylamine, and 2-methylbutylamine were identified, which may be derived from valinyl, leucinyl, and isoleucinyl residues, respectively. Additionally, tyramine possibly derived from tyrosyl residues was identified in the digests of all the crude drugs. In primary cultured rat hepatocytes treated with interleukin-1β, all these decarboxylated amino acids suppressed the production of nitric oxide, a proinflammatory mediator. Our approach, i.e., in vitro protease digestion and LC-MS/MS analysis, suggests that decarboxylated amino acids may be formed in vivo from peptides and may be responsible for the anti-inflammatory effect of crude drugs included in Kampo medicine.

Elemental diet directly affects chemotherapy-induced dermatitis and raw wound areas

Elental^® is an L-glutamine-rich elemental diet (ED) that has been widely used in Japan as a nutritional supplement for malnourished patients. In addition, Elental^® has been successfully used in the management of chemotherapy-induced mucositis in cancer patients. Recently, it was also reported that Elental^® can effectively reduce chemotherapy-induced oral mucositis in patients with oral squamous cell carcinoma, and can also reduce mucositis and dermatitis in animal models. However, it is unclear whether oral intake or topical application of Elental^® can act directly on chemotherapy-induced oral mucositis or dermatitis. The aim of the present study was to investigate the possible direct healing effect of Elental^® on chemotherapy-induced dermatitis and raw wound areas in a mouse model. Dermatitis and raw wounds were induced in nude mice by administration of 5-fluorouracil (5-FU) (via gastric tube) and mechanical injury (using a metal brush or a surgical knife). We then compared the outcome following oral or topical application of Elental^® in these mice. The effect of Elental^® on the growth and migration ability of the human oral keratinocyte cell line, HOK, was also examined using MTT and migration assays, respectively. In the mouse model, both oral administration and topical application of Elental^® reduced 5-FU-induced dermatitis and healed raw wound areas more effectively compared with the topical application of saline. The MTT assay revealed that Elental^® exerted a growth-promoting effect on HOKs. In addition, Elental^® enhanced the ability of HOKs to migrate, as demonstrated by the migration assay. These findings demonstrated that the topical application as well as the oral intake of Elental^® exerted a direct healing effect on chemotherapy-induced dermatitis or raw wound areas. The data also indicated that oral intake of an ED may exert a direct healing effect on chemotherapy-induced oral mucositis.