Characterization of Local and Systemic Events after Oral Coadministration of Chitosan and Type II Collagen: Induction of Anti-Inflammatory Cytokines

CARINA PORPORATTO; CLELIA M RIERA; SILVIA G CORREA

Montreal, Canada

Congreso; 12TH INTERNATIONAL CONGRESS OF IMMUNOLOGY AND 4TH ANNUAL CONFERENCE OF FOCIS; 2004

International Union of Immunological Societies

ABSTRACT: RATIONALE. The intestinal microenvironment and the cytokine milieu condition the mucosal immune response to orally administered antigens. Chitosan (Q) is a natural polysaccharide able to promote the transmucosal absorption of peptides and proteins by bioadhesion and widening of epithelial tight junctions. Besides, Q improves local and systemic immune responses to coadministered or encapsulated antigens by a poorly understood mechanism. Here we evaluated local and systemic events after oral coadministration of Q and the articular antigen type II collagen (CII). METHODS. We fed Wistar rats a single 200 ¥ìl dose of diluent, 1 mg Q, 1 mg CII or CII:Q (1mg each). Sixteen h later we prepared cell suspensions of Peyer patches (PP), mesenteric lymph nodes (MLN) and spleen to assess the expression of CD71 and CD54 markers and the down-modulation of the CD3 complex on T cells (flow cytometry); the arrival of CII to spleen (antigen presentation assay) and the induction of the regulatory cytokines IL-10, IL-4 and TGF-¥â by ELISA, flow cytometry and RT-PCR. Additionally, we evaluated location and phenotype of cells involved in the uptake of Q after feeding 1 or 3 mg of FITC-Q (flow cytometry). RESULTS. Sixteen h after feeding we found a significant increment in the % of internal CD3 in spleen cells of CII:Q group (p< 0.05) with no differences in PP or MLN. The % of CD3+CD71+ and CD3+CD54+ cells increased in spleen of Q fed rats (p<0.05). Spleenocytes of CII fed rats stimulated the proliferation of CII-specific T cells (p<0.01 vs. diluent) but not cells from CII:Q fed group. In PP, CII:Q fed rats showed increased levels of mRNA for TGF-¥â, IL-4 and IL-10. Interestingly, Q itself stimulated the release of IL-10 in PP, MLN and spleen. A significant negative correlation between uptake of FITC-Q (r= -0.69; p= 0.01) and gut segment was obtained. Early after feeding FITC-Q, 20% of positive cells were in PP and 5% in MLN and spleen. Most Q-loaded cells expressed the CD11b/c marker. CONCLUSION. The oral coadministration of CII with chitosan modifies the uptake and or the distribution of CII and promotes an anti-inflammatory environment that conditions the immune response to CII. The uptake of chitosan takes place at the upper portion of the small gut mainly by CD11b/c positive cells.