Function of the gut immune system and biogenic amines

The lamina propria layer of the intestinal wall contains a high concentration of plasmocytes, which produce immunoglobulins

The intestinal immune system is stimulated by the intestinal flora. Normal intestinal flora is essential for optimal immunity, as reduced immunity, macrophage activity, and underdeveloped lymphoid tissue can occur without it.

In response to the antigenic load of the intestinal lumen, a fourfold defence system suppresses and displaces pathogenic bacteria

The system is composed of four components. Biogenic amines, formed from free amino acids, cannot be defended against by the intestinal immune system. The defence system comprises four elements: microbial, humoral, anatomical, and cellular. It primarily defends against cellular elements and protects antigenic microbial protein compounds. However, these barriers are ineffective against toxic, non-antigenic compounds such as biogenic amines and microtoxins.

Local immune stimulation occurs

in the intestine due to the presence of immunobiologically active components in the cell wall of bacteria, including peptidoglycan (PG) in Gram-negative and Gram-positive bacteria and lipopolysaccharide (LPS) in the cell wall of Gram-negative bacteria. LPS has a 1000-fold higher immunobiological activity.

The immune system functions at a basic level. Specific protection develops only after exposure to the appropriate antigen. The immune system requires continuous stimulation from LPS and PG stimulators found in the intestinal flora to develop properly and maintain good health. Small amounts of LPS entering the bloodstream are beneficial to the host, as they stimulate the immune system and improve cellular defence.

Fermentation by-products, such as amino acids and sodium glutamate, are produced through the fermentation of other food additives. Corynebacterium glutamicum bacteria are responsible for fermenting both threonine amino acid and sodium glutamate.

An acute systemic immune reaction is triggered when a significant amount of LPS enters the bloodstream, leading to a general inflammatory process.

These substances contain biogenic amines that can affect the health of farm animals

The globalised feed industry has introduced new feed ingredients into piglet feed over the last decade and a half. Consequently, piglets are exposed to substances that were not previously present in their feed. In 2010, the global pharmaceutical, food, and feed sectors produced over 100 million tonnes of fermented amino acids, artificial food additives, and their fermentation by-products. The animal feed industry currently utilises fermented amino acids and artificial flavour enhancers, as well as their by-products, as raw materials.

By-products from the fermentation industry are also commonly used as feed for pigs, fattening, and sow. These by-products are a typical feature of the fermentation process. Additionally, fermentation processes produce various intermediate products, such as free amino acids, di- and polypeptides, and biogenic amines. The by-products are of particular importance. The feed materials contain billions of dead bacterial bodies from fermenting bacteria. For instance, the bacterium E. coli ferments the artificially produced amino acid threonine.

Biogenic amines (BA) are formed by the decarboxylation of amino acids

There are exogenous (supplied with the feed) and endogenous (produced in the animal) biogenic amines. These are involved in the fine regulation of the body and are known as tissue hormones. Biogenic amines are neurotransmitters that are involved in the transmission of stimuli. Their quantity in the body is fixed and regulated. Any other quantity raises unexplained toxicological problems.

Biogenic amines are obtained from amino acids by oxidative decarboxylation:

• Arginine – Agmatine, Putrescine
• Hisztidine – histamine
• Lizin – cadaverine
• Methionine – spermine and spermidine
• Ornitine – putrescine
• Phenylalanine – Phenylethylamine
• Tryptophan – Triptamine, serotonin
• Tirozine – tiramine

The presence of large quantities of biogenic amines in the blood puts a strain on the liver. The liver can only partially detoxify the amines, which leads to a variety of liver problems. Biogenic amines are direct cellular and neurotoxins and paralyse the autonomic nerves that innervate the vascular network.

Read the article in German: Funktion des Darmimmunsystems und biogene Amine