Effect of ochratoxin A on the intestinal mucosa and mucosa-associated lymphoid tissues in broiler chickens

The immunotoxic effect of ochratoxin A (OTA) on the intestinal mucosa-associated lymphoid tissue and its cytotoxic action on the intestinal epithelium were studied in broiler chickens experimentally treated with the toxin. From the 7th day of life, 80 male broiler chickens (Ross 308) were randomly divided into four groups of 20 birds each. The three experimental groups (E1-3) were treated with OTA for 28 days (E1: 50 μg/kg body weight [bw]/day; E2: 20 μg/kg bw/day; E3: 1 μg/kg bw/day) and the fourth group served as control. Histological examination of the intestinal mucosa and immunohistochemical staining for identification of CD4+, CD8+, TCR1 and TCR2 lymphocytes in the duodenum, jejunum and ileocaecal junction were performed, and CD4+/CD8+ and TCR1/TCR2 ratios were calculated. OTA toxicity resulted in decreased body weight gain, poorer feed conversion ratio, lower leukocyte and lymphocyte count, and altered intestinal mucosa architecture. After 14 days of exposure to OTA, immunohistochemistry showed a significant reduction of the lymphocyte population in the intestinal epithelium and the lamina propria. After 28 days of exposure, an increase in the CD4+ and CD8+ values in both the duodenum and jejunum of chickens in Groups E1 and E2 was observed, but the TCR1 and TCR2 lymphocyte counts showed a significant reduction. No significant changes were observed in Group E3. The results indicate that OTA induced a decrease in leukocyte and lymphocyte counts and was cytotoxic to the intestinal epithelium and the mucosa-associated lymphoid tissue, altering the intestinal barrier and increasing susceptibility to various associated diseases

Malabsorption Disorders

Malabsorptive symptoms can be caused by a variety of medications and immune-mediated, infectious, and genetic disorders that share a final common pathway resulting in decreased small-intestinal surface area. Many immune-mediated and medication-related conditions cause a malabsorptive histologic pattern of injury characterized by villous blunting, intraepithelial lymphocytosis, and mononuclear cell-rich inflammation in the lamina propria. Others features include prominent epithelial cell injury, crypt cell apoptosis, and crypt destruction. Correct classification of these disorders requires knowledge of their distinctive histologic features, presenting symptoms and medical history, serologic studies, distribution of disease, and endoscopic findings. The purpose of this chapter is to address frequently asked questions that arise when evaluating biopsy or resection samples from patients with clinical features of intestinal malabsorption and offer suggestions regarding the pathologic reporting of these cases