Oral Administration of Mice with Cell Extracts of Recombinant Lactococcus lactis IL1403 Expressing Mouse RANKL

Biao Xuan1, Jongbin Park1, Geun-Shik Lee2, Eun Bae Kim1,*
Author Information & Copyright
1Department of Applied Animal Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea.
2College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea.
*Corresponding Author: Eun Bae Kim, Department of Applied Animal Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea. E-mail:

© Copyright 2022 Korean Society for Food Science of Animal Resources. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Jun 13, 2022 ; Revised: Aug 08, 2022 ; Accepted: Sep 05, 2022

Published Online: Sep 06, 2022


Receptor activator of NF-kB ligand (RANKL) is known to play a major role in bone metabolism and the immune system, and its recombinant form has been expressed in bacterial systems for research since the last two decades. However, most of these recombinant forms are used after purification or directly using living cells. Here, there were cell extracts of recombinant Lactococcus lactis expressing mouse RANKL (mRANKL) used to evaluate its biological activity in mice. Mice were divided into three groups that were fed phosphate-buffered saline (PBS), WT_CE (wild-type L. lactis IL1403), and mRANKL_CE (recombinant L. lactis expressing mRANKL). The small intestinal transcriptome and fecal microbiome were then profiled. The biological activity of mRANKL_CE was confirmed by studying RANK-RANKL signaling in vitro and in vivo. For small intestinal transcriptome, differentially expressed genes (DEGs) were identified in the mRANKL_CE group, and no DEGs were found in the WT_CE group. In the PBS vs. mRANKL_CE gene enrichment analysis, upregulated genes were enriched for heat shock protein binding, regulation of bone resorption, and calcium ion binding. In the gut microbiome analysis, there were no critical changes among the three groups. However, Lactobacillus and Sphingomonas were more abundant in the mRANKL_CE group than in the other two groups. Our results indicate that cell extracts of recombinant L. lactis expressing mRANKL can play an effective role without a significant impact on the intestine. This strategy may be useful for the development of protein drugs.

Keywords: Cell extracts; RANKL; L. lactis; transcriptome; microbiome