Phytohemagglutinin-induced diarrheal disease

Abstract

A purified plant lectin, phytohemagglutinin (PHA), or crude red kidney bean (RKB) from which it was derived, when incorporated as 1% of dietary protein into a purified casein protein diet caused weanling rats to fail to grow or lose weight in comparison to control animals pair fed an isonitrogenous, isocaloric diet. Feeding PHA was observed to cause diarrhea: fecal wet and dry weights were increased within 2 days after starting the diet. Increased fecal weight was caused by increased dry weight as well as by an increased fecal water content. On reversion to a normal casein diet, rapid amelioration of the antinutritional effects of PHA occurred with resumption of normal growth rate. Specific binding of PHA to the microvillus region of the small intestinal epithelium was demonstrated using rabbit anti-PHA and fluorescein-labeled goat anti-rabbit immunoglobin. PHA binding was observed after chronic intake in the diet or when applied to normal tissue in vitro. Loss of PHA binding to the intestine was observed to occur within 48 hr on reversion to a control casein diet. No significant morphological damage to the microvilli or the mucosal villus architecture was observed to accompany PHA adherence under these experimental conditions. Antinutritional and antiabsorptive effects of dietary PHA were associated with diarrhea. PHA adhered to the microvillus membrane of the small intestinal villus surface during the diarrheal state.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of Lectin (Phytohemagglutinin)-Induced Growth in Small Intestinal Epithelial Cells

“…Yet, human Intestine-407 cells might be more resistant to treatment with higher concentrations of PHA due to a longer doubling time. In vivo, the toxic effects of high doses of PHA included symptoms like diarrhea, malabsorption and loss of weight [4, 14]. In some studies these toxic effects of PHA were thought to be associated with bacterial overgrowth [7, 13].…”

“…Yet, besides growth-promoting effects, high concentrations of PHA (up to 6% of dietary protein) have been shown to cause villus blunting, mucosal inflammation and shortening of microvilli. Treated animals suffered from loss of weight, malabsorption and diarrhea [13, 14, 15]. …”

Sucrose Co-administration Reduces the Toxic Effect of Lectin on Gut Permeability and Intestinal Bacterial Colonization

“…This binding of legume lectins to cell surface proteins is central to its toxic effects of disrupting barrier function as shown by a loss of epithelial resistance, reducing brush border enzyme activity and distorting villous architecture [5][6][7][8]. These effects are responsible for acute gastrointestinal symptoms similar to those triggered by an infectious gastroenteritis and other food poisoning and may lead to maldigestion, malabsorption, loss of appetite and weight loss in humans [9][10][11][12] and animals [5,13]. The potential toxicity of legume lectin is further demonstrated by death in animals experimentally fed raw red kidney beans for a protracted period.…”

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…In other animals, soybean or other plant lectins have also been reported to cause hyperplastic growth of intes ajiri et Pusztai et al, 1990;Bardocz et al, 1992 andBanwell et a 1993); decreased cell turnover time (Pusztai et al, 1990); uptake of lectin via endocytosis intestinal epithelial cells (Pusztai et al, 1981;Banwell et al, 1984;King et al, 1986;Bardoc et al, 1995); changes in pancreatic weight and enzyme secretion (Greer and Pusztai, 1985;Huisman et al, 1990;Banwell et al, 1993;Pusztai et al, 1993a;Grant et al, 1997); changes in liver weight (Oliveira et al, 1988;Aletor, 1989); reduced plasma insulin levels (Knott et al, 1992;Bardocz et al, 1996;Pusztai et al, 1998); increased cholecystokinin (CCK) release (Jordinson et al, 1996 and; and reduced skeletal muscle mass (Oliveira et al, 1988;Bardocz et al, 1992).…”