The influence of a colonic microbiota on HPMA copolymer lectin conjugates binding in rodent intestine

Germ-free (GF) animals lack a colonic microflora like that seen in conventi onal (CV) animals. Bacterial presence plays a role in the development of gl ycoproteins in the gastrointestinal (GI) tract; the absence of a microbiota has been seen to suppress the production of certain glycoproteins and glyc olipids. Binding patterns of lectins are modified when glycoprotein structu res are altered (e.g., during development or disease). Little information o n lectin binding patterns in mature GF animals is available. We examined th e binding of free and N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-co njugated fluorescein isothiocyanate (FITC)-labeled wheat germ agglutinin (W GA) [P(HPMA)-(WGA-FITC)] and FITC-labeled peanut agglutinin (PNA) [P(HPMA)- (PNA-FITC)] in CV and GF mouse colon with and without neuraminidase pretrea tment. Anti-Thomsen-Friedenreich (TF) antigen (a development and disease-re lated glycoprotein) antibody binding was also examined in these tissues. Su btle differences were seen in the binding patterns between CV and GF animal s. CV animals showed strong P(HPMA)-(WGA-FITC) binding in goblet cells, but minimal P(HPMA)-(PNA-FITC) binding was visible. In GF animals, luminal sur face binding of P(HPMA)-(WGA-FITC) was visible, and goblet cell binding of P(HPMA)-(PNA-FITC) was seen. These subtle changes suggest that altered glyc oprotein expression occurred under GF conditions.