Modulation by bovine lactoferrin of parameters associated with the IgA response in the proximal and distal small intestine of BALB/c mice

Abstract

Background: Secretory IgA (SIgA) and the polymeric immunoglobulin receptor (pIgR) have a pivotal role in gut homeostasis. Bovine lactoferrin (bLf) has been shown to modulate intestinal immunity and endogenous corticosterone. Considering the regionalization of the intestinal immune response, the aim of this work was to compare the impact of bLf on the IgA response in the proximal versus distal small intestine under physiological conditions.

Methods: Groups of healthy male BALB/c mice were orally treated with one daily dose of bLf (50, 500, or 5000 μg) or untreated (control) for 7 d, and then sacrificed. From plasma samples, corticosterone levels were determined by an enzyme-linked immunosorbent assay (ELISA) kit. From distal and proximal segments of the small intestine, the following material was obtained: intestinal secretions to evaluate IgA levels by ELISA; epithelial cell extracts for protein-analysis of α-chain and pIgR by Western blot; mucosa samples for mRNA analysis of α-/J-chain, pIgR, and interleukin (IL)-2, -4, -5, and -6 by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR).

Results: With 5000 μg of bLf, there were greater modulatory effects in the distal (versus proximal) segment, evidenced by an increase in the (i) level of total and specific IgA, (ii) protein expression of α-chain and pIgR, (iii) mRNA transcripts of α-chain, IL-2 and IL-5, and (iv) level of plasma corticosterone.

Conclusions: Endogenous corticosterone elicited by bLf may have allowed for an IL profile that favored the IgA antibody response. The latter has a key role in maintaining intestinal homeostasis.

Keywords:

• Bovine lactoferrin
• IL-2
• IL-5
• pIgR
• SIgA

Acknowledgements

This work was supported by grants from Consejo Nacional de Ciencia y Tecnología [No. 167345] and Secretaría de Investigación y Posgrado, Instituto Politécnico Nacional [No. 20161692]. The authors with affiliation in the ESM, Instituto Politécnico Nacional, are fellows of COFFA and EDI-IPN.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by grants from Consejo Nacional de Ciencia y Tecnología [No. 167345] and Secretaría de Investigación y Posgrado, Instituto Politécnico Nacional [No. 20161692].