Lactobacillus plantarum Enhanced IL-22 Production in Natural Killer (NK) Cells That Protect the Integrity of Intestinal Epithelial Cell Barrier Damaged by Enterotoxigenic Escherichia coli.

Xianyong Ma,Shenglan Hu,Zongyong Jiang,Xuefen Yang,Yueqin Qiu,Li Wang

doi:10.3390/ijms18112409

Abstract

Interleukin (IL)-22-producing Natural Killer (NK) cells protect the gut epithelial cell barrier from pathogens. A strain of probiotics, Lactobacillus plantarum (L. plantarum, LP), was previously found by our laboratory to significantly improve the mucosal barrier integrity and function of the small intestine in pigs. However, it was unclear whether LP benefited the intestinal mucosal barrier via interactions with the intestinal NK cells. The present study, therefore, was focused on the therapeutic effect of NK cells that were stimulated by LP on attenuating enterotoxigenic Escherichia coli (ETEC)-induced the damage to the integrity of the epithelial cell barrier. The results showed that LP can efficiently increase protein levels of the natural cytotoxicity receptor (NCR) family, and the expression levels of IL-22 mRNA and protein in NK cells. Transfer of NK cells stimulated by LP conferred protection against ETEC K88-induced intestinal epithelial barrier damage in NCM460 cells. We found that NK cells stimulated by LP could partially offset the reduction in NCM460 cell monolayers transepithelial electrical resistance (TEER) caused by ETEC K88, and increase ZO-1 and occludin mRNA and protein expressions by ETEC K88-infected NCM460 cells. Furthermore, adding NK cells that were stimulated by LP to ETEC K88-infected NCM460cells, IL-22R1, p-Stat3, and p-Tyk2 expression by NCM460 cells was increased. Mechanistic experiment showed that NK cells stimulated by LP lost the function of maintaining TEER of NCM460 cells challenged with ETEC K88, when polyclonal anti-IL-22 antibody was used to block IL-22 production. Collectively, our results suggested that LP stimulation of NK could enhance IL-22 production, which might be able to provide defense against ETEC-induced damage to the integrity of intestinal epithelial barrier.

Highlights

The intestinal epithelium barrier plays an important role in separating the internal from the external environment, providing the major physical barrier against the invasion and diffusion of enteropathogenic microorganisms [1]
DiKffiellreer n(Nt Kco) Cneclelsntrations of LP increased the protein level of NCR3, but there was no effect of LP on the exDpifrfeesresniotncoonfceNnCtraRt1io,nasnodf LoPnliyncarehaisgedhethrecopnrocteenintrleavtieol nofoNf C10R93,CbFuUt t/hmereLwoafsLnPo eelfefevcat toefd the NCR2 pLrPootenintheleevxeplraests2iohn o(Ff iNgCuRre1,1abn–ddo).nlAy fatehrig4hheracnodnc6enhtraotfioinncouf b1a09tiCoFnUw/mitLhoLfPLP(1e0l8ev, a5te×d 1th0e8 and 1p0ro9 tCeiFnUpCNl/reFCovmURtee/2Llimsn)pL,wlre)eo,vexteeerpxelisnrpeswrliseegesvsnriseoeiilofinsanictgoao2nfnfiNhftNilc(yCFaCnRieRgtn2ul2yhrppeaerrnn1oohcbtteaee–inddinnc)b.ewwdAyaafbLstsyePmrmL4(aP5arhkr(×5keaden×1ldd1y0l068yi8nhaaicnnnrodcedfari1es1n0ea0c9ds9uCeb(CdFFaUFit(giUFo/umni/rgeLwmu)1riaLcteht)).14LaTcaPth)n.4e(d1TaN06hn8C,ehd5RN(6F×1Cih1ga0Rnu(8drF1aeinaNg1dnubCd,r1dRe0)N39.1Cb,Rd3)
LImP aplorntea.ntly, we found that Natural Killer (NK) cells stimulated by 109 CFU/mL LP in the presence of polyclonal anti-IL-22 antibody against IL-22, but not control goat IgG, led to significant decreases in Trans-Epithelial Electrical Resistance (TEER) of NCM460 cell monolayers challenged with enterotoxigenic Escherichia coli (ETEC) K88, when compared with cells stimulated by LP alone

Summary

Introduction

The intestinal epithelium barrier plays an important role in separating the internal from the external environment, providing the major physical barrier against the invasion and diffusion of enteropathogenic microorganisms [1]. Pathogens such as Escherichia coli (ETEC) can decrease the expression of tight junction proteins, and disrupt the tight junction structures of the mucosal barrier, leadingInta. L20d17e, f1e8,c2t40o9f the intestinal barrier function [2,3]. Lodemann and cowork2eorfs14have demonesntrtaertoepdatthhoagteEnTicEmCicKro8o8rgcaannismafsfe[c1t].thPaethboagrerniesrsfuucnhcatsioEnscohferbicohtiahcpoloi r(cEiTnEeCa)ncdanhduemcraenaseinttheestinal epithelieaxlpcreesllssio[n4]o.fAtigshttujdunycbtiyonYpuroatnedinsc,oawndordkiserruspatltshoe stihgohwt juednctthioantsEtrTuEctCurKes8o8fitnhde umcuecdosdaal mbaarrgieert,o the integritlyeaodfinhgumananinCitiaacl od-e2feccetllosf[5th].e intestinal barrier function [2,3].

Methods

Results

Conclusion