Use of toll-like receptor-expressing cells
Swine Toll-like receptor 9 (TLR9)-expressing cells are prepared by cloning a TLR9 gene from swine intestinal Peyer's patches. Functional analysis on CpG DNAs using the above cells revealed that swine TLR9 shows a higher recognition ability for a human CpG DNA motif (CpG2006) than for a mouse-specific CpG DNA motif (CpG1826). When the mRNA expression levels in various tissues are compared by the real-time PCR method, it is found out that the mRNA is expressed in Peyer's patches and mesenteric lymph nodes, which play important roles in the intestinal tract immune system, at a level thrice as much as in spleen or more. Thus, the cells expressing an intestinal tract tissue-expressed TLR (for example, TLR9) can be used to identify samples capable of activating the intestinal tract immune system.
1. A method of screening for a sample that activates the intestinal tract immune system, comprising the steps of:
(a) contacting a test sample with an isolated cell expressing a Toll-like receptor 9 (TLR9) encoded by a DNA comprising the nucleotide sequence shown in SEQ ID NO: 1;
(b) measuring activity of the TLR9 using signal transduction in the cell as an indicator; and
(c) selecting the test sample as a sample that activates the intestinal tract immune system if the activity of the TLR9 is increased as compared to activity of the TLR9 in a cell not contacted with the test sample.
2. A method for producing a pharmaceutical composition that activates the intestinal tract immune system, comprising the steps of claim 1 , and a further step of mixing the sample selected as a sample that activates the intestinal tract immune system with a pharmaceutically acceptable carrier.
3. A method of screening for microorganisms that activate the intestinal tract immune system, comprising the steps of:
(a) preparing an extract from a test microorganism;
(b) contacting the extract with an isolated cell expressing a Toll-like receptor 9 (TLR9) encoded by a DNA comprising the nucleotide sequence shown in SEQ ID NO: 1;
(c) measuring activity of the TLR9 using signal transduction in the cell as an indicator; and
(d) selecting the test microorganism as a microorganism that activates the intestinal tract immune system if the activity of the TLR9 is increased as compared to activity of the TLR9 in a cell not contacted with the extract.
4. A method for producing a food composition that activates the intestinal tract immune system, comprising the steps of claim 3 , and then mixing the microorganism selected in part (d) of claim 3 with a dietarily acceptable carrier.
5. The method of claim 4 , wherein the microorganism is a lactic acid bacterium.
6. The method, according to claim 4 , wherein the dietarily acceptable carrier is a dairy product.