Immunohistochemical Localization of Transforming Growth Factor-Alpha in Suckling Porcine Intestine

Abstract

The distribution of transforming growth factor-alpha (TGFα), a member of the epidermal growth factor (EGF) family, was studied immunohistochemically in small intestinal tissues of suckling pigs which were 7, 14 and 21 days of age. TGFα immunostaining was similar in villous epithelium in all intestinal regions of all ages examined, and was diffuse throughout the epithelial cytoplasm and more prominent in the apical and brush-border regions of the cells. Cytoplasmic immunoreactive TGFα was also identified in crypt epithelial cells; the pattern and extent of immunostaining differed among intestinal regions and ages. In all cases, the relative number of TGFα-immunopositive crypt epithelial cells was fewer than the number of immunonegative cells within the compartment. In duodenal and jejunal segments, relative numbers of immunopositive crypt epithelial cells were greater in 14- and 21- than in 7-day-old pigs. In all 7-day-old pigs, a relatively greater number of immunopositive epithelial cells was present in the jejunal crypts than in the duodenal crypts. Intracellular TGFα immunostaining was present within Peyer’s patches of distal jejunum and ileum, and is a previously unreported finding. The presence of TGFα immunoreactive protein within small intestinal crypt epithelium has not been previously described in any species, and may be unique to suckling animals or, alternatively, the porcine species. These data suggest that TGFα may be an endogenous ligand for the EGF receptor in suckling porcine intestine. Increased expression of TGFα in suckling pigs during the period in which marked structural and functional changes occur within the small intestinal mucosa suggests a role for this growth factor in remodelling and maturation of the neonatal mucosa.

Milk growth factors and expression of small intestinal growth factor receptors during the perinatal period in mice

“…Immunohistochemical localization of TGF-α in porcine intestine showed that expression is greater at PD14 and 21 than in PD7 piglets (37). TGF-α belongs to the EGF family and binds to the EGF receptor (37). If TGFα regulates EGF receptor expression significantly, its decrease by PD14 may be explained.…”

“…A study on rat duodenum found that endogenous TGF-β1 production is low at birth, but increases after mid-weaning (36). Immunohistochemical localization of TGF-α in porcine intestine showed that expression is greater at PD14 and 21 than in PD7 piglets (37). TGF-α belongs to the EGF family and binds to the EGF receptor (37).…”

Small Bowel Review: Part II

“…TGF-a stimulates proliferation of rat intestinal tissue during the developmental period (48). TGF-a immunoreactive protein is present in the small intestinal crypt epithelium in suckling pigs (49). TGF-a and TGF-b play a role in the repair of the intestine after phytohemagglutinin-induced acute epithelial injury (47).…”