Paneth cell degranulation and lysozyme secretion during acute equine alimentary laminitis

Abstract

The equine Paneth cell response to a shift in the microbial balance of the intestinal tract was studied by inducing an acute episode of alimentary laminitis in 6 mature ponies. The normal bacterial population of the gut was modified by administration of a carbohydrate-rich ration. During acute laminitis a dramatic degranulation of the Paneth cells occurred in the intestinal glands throughout the duodenum, jejunum, and ileum. Bacteriocidal lysozyme, which was immunohistochemically identified as a component of the Paneth cell secretory granule, was evident in the glandular lumina and in degranulated Paneth cells. These results indicate that lysozyme is secreted by the equine Paneth cell in an apparent attempt to regulate the changing microbial population induced by carbohydrate overload of the gut. From these observations, it is suggested that the Paneth cell plays a role in the mucosal defense system of the equine intestinal tract.

Detection of Deoxyribonuclease I Along the Secretory Pathway in Paneth Cells of Human Small Intestine

“…The bacterial environment of the gut lumen has a direct effect on Paneth cell secretory activity (Masty and Stradley 1991). Several classes of antimicrobial peptides have also been identified in the mammalian small intestine.…”

“…They have also been suggested to be involved in heavy metal elimination (Kodama et al 1993;Sawada et al 1994) and regulation of crypt cell growth (Cheng and Leblond 1974;Mathan et al 1987). Furthermore, Paneth cells are believed to be involved in the regulation of the intestinal flora because they are able to phagocytose microorganisms (Masty and Stradley 1991;Leis et al 1997). The histochemical localization of IgG and IgA in Paneth cells was interpreted as probably reflecting an opsonization phenomenon (Rodning et al 1976;Coutinho et al 1996).…”

The multifaceted Paneth cell

“…PCs also contain pancreatitis-associated protein, PAP (also known as hepatocarcinoma-intestinepancreas protein, HIP) [69,70], belonging to a family of C-type lectins that bind sugar moieties on microbial surfaces with consequent aggregation or enhanced binding to phagocytes. Upon exposure to viable or heat-killed bacteria [53,68] or to microbial products such as lipopolysaccharide and lipoteichoic acid [50,71], PCs release their granules, resulting in increased concentrations of antimicrobials in the intestinal lumen. Hence, PCs may be important in controlling microbial density in the small intestine where microbial nutrients in the form of digestate are plentiful.…”

“…3). Other granule proteins with possible but less well defined antimicrobial roles include the weakly antimicrobial secretory leukocyte inhibitor (SLPI) [67] and immunoglobulin IgA [68] that 185], ostrich [192], mouse [174 -176], rat [177,178], mole [185], anteater [190], sloth [193], seal [194], crocodile [195], rabbit [12], guinea pig [12,117], echidna [191] colubrid snake [196] hamster [12,129,179], horse [53,186] may bind to and block microbial pathogenic factors such as pili or toxins. PCs also contain pancreatitis-associated protein, PAP (also known as hepatocarcinoma-intestinepancreas protein, HIP) [69,70], belonging to a family of C-type lectins that bind sugar moieties on microbial surfaces with consequent aggregation or enhanced binding to phagocytes.…”

Detection of CD1 mRNA in Paneth cells of the mouse intestine by in situ hybridization.

“…The bacterial environment of the gut lumen has a direct effect on Paneth cell secretory activity (59)(60)(61). The immunohistochemical localization of IgA or IgG in Paneth cells was interpreted as probably reflecting an opsonization phenomenon preceding internalization of infec- In the adult mouse, some y16 T-cell subpopulations show a predilection for epithelia (32).…”