Swine-Derived Probiotic Lactobacillus plantarum Inhibits Growth and Adhesion of Enterotoxigenic Escherichia coli and Mediates Host Defense

Abstract

Weaning stress renders piglets susceptible to pathogen infection, which leads to post-weaning diarrhea, a severe condition characterized by heavy diarrhea and mortality in piglets. Enterotoxigenic Escherichia coli (ETEC) is one of typical strains associated with post-weaning diarrhea. Thus, prevention and inhibition of ETEC infection are of great concern. Probiotics possess anti-pathogenic activity and can counteract ETEC infection; however, their underlying mechanisms and modes of action have not yet been clarified. In the present study, the direct and indirect protective effects of Lactobacillus plantarum ZLP001 against ETEC infection were investigated by different methods. We found that bacterial culture and culture supernatant of L. plantarum ZLP001 prevented ETEC growth by the Oxford cup method, and ETEC growth inhibition was observed in a co-culture assay as well. This effect was suggested to be caused mainly by antimicrobial metabolites produced by L. plantarum ZLP001. In addition, adhesion capacity of L. plantarum ZLP001 to IPEC-J2 cells were observed using microscopy and counting. L. plantarum ZLP001 also exhibited a concentration-dependent ability to inhibit ETEC adhesion to IPEC-J2 cells, which mainly occurred via exclusion and competition mode. Furthermore, quantitative real time polymerase chain reaction (qPCR) analysis showed that L. plantarum ZLP001 upregulated the expression of host defense peptides (HDPs) but did not trigger an inflammatory response. In addition, L. plantarum ZLP001 induced HDP secretion, which enhanced the potential antimicrobial activity of IPEC-J2 cell-culture supernatant after incubation with L. plantarum ZLP001. Our findings demonstrate that L. plantarum ZLP001, an intestinal Lactobacillus species associated with piglet health, possesses anti-ETEC activity. L. plantarum ZLP001 might prevent ETEC growth, inhibit ETEC adhesion to the intestinal mucosa, and activate the innate immune response to secret antimicrobial peptides. L. plantarum ZLP001 is worth investigation as a potential probiotics.

Effects of Lactobacillus plantarum on the intestinal morphology, intestinal barrier function and microbiota composition of suckling piglets

“…and pBD3) were upregulated after exposure to L. plantarum ZLP001 in IPEC-J2 cells (Wang, Zeng, et al, 2018), suggesting that L. plan- (Liu et al, 2010;Yi et al, 2018). We observed that the L. plantarum 299v treatment significantly increased the mRNA levels of ileal TLR2, TLR4, TLR6 and TLR9 but did not change the levels of jejunal TLRs.…”

“…A previous study indicated that supplementation with L. plantarum CGMCC 1,258 resulted in higher levels of occludin mRNA in the jejunum of young piglets (Yang, Jiang, Zheng, Wang, & Yang, ). In vivo, L. plantarum ZLP001 treatment alleviated the reduced expression of claudin‐1 , occludin and ZO‐1 caused by ETEC (Wang, Zeng, et al, ). These data indicated that L. plantarum could improve the expression of TJs proteins in the intestine.…”

“…Our data demonstrated that the mRNA expression of intestinal pBD1, pBD2 and pBD3 was higher in the L. plantarum 299v group than in the control group. Additionally, Wang et al reported that the mRNA levels of pBDs (including pBD1, pBD2 and pBD3 ) were upregulated after exposure to L. plantarum ZLP001 in IPEC‐J2 cells (Wang, Zeng, et al, ), suggesting that L. plantarum effectively stimulates porcine HDP secretion in vivo and in vitro. The gastrointestinal function of suckling piglets is weak, and they often suffer from diarrhoea.…”

“…Diet with L. plantarum ‐fermented wheat also can improve the apparent total tract digestibility of nutrients and energy, nitrogen retention, and energy content of weaned piglets (Koo, Bustamante‐García, & Nyachoti, ). In vitro, L. plantarum is reported to protect the epithelial barrier disruption caused by enterotoxigenic Escherichia coli (ETEC) in intestinal porcine epithelial cells (Wang, Zeng, et al, ; Wu et al, ). The neonatal period is a critical time to establish a stable, lifelong host–microbial homeostasis; colonization by beneficial bacteria is important for maintaining the intestinal mucosal barrier and protecting the neonates from pathogens and inflammation (Sohn & Underwood, ; Stockinger, Hornef, & Chassin, ).…”

Health promoting activities of probiotics

“…For instance, L. rhammosus GG exhibited excellent mucus adhering characteristics partly due to its specific pili SpaCBA (Hampe & Roth, ). Therefore, probiotics may preoccupy and compete for pathogen‐binding sites, leading to interference with pathogenic adhesion and resistance colonization (Wang et al, ). Some oral pathogenic strains like Streptococcus mutans and S. sobrinus forming biofilm give rise to the development of dental caries.…”