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The usefulness of Caco-2 cell monolayers in determining the intestinal drug absorption of potential drug candidates as such and from delivery systems, elucidating the underlying mechanisms thereof, presystemic metabolism, cellular uptake and cytotoxicological assessment has been exemplified in this review. The role of Caco-2 cell monolayers in studying the effectiveness, involved mechanism and toxicity of various excipients for drug absorption promotion has also been discussed.

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Lactobacilli isolated from various sources were identified on the basis of 16S -23S rRNA gene intergenic region amplification and subsequent sequencing of the smaller intergenic region. An in vitro analysis of probiotic properties including binding, ability to tolerate different concentrations of bile, survival in acidic buffer and antimicrobial activity of four different isolates and two standard strains (Lactobacillus plantarum American Type Culture Collection (ATCC) 8014 and L. rhamnosus GG (LGG)) was carried out. The ability of each isolate to stimulate Caco-2 cells, human peripheral blood mononuclear cells (PBMC) and THP-1 cells resulting in immunomodulation of these cells was analysed. Isolates L. rhamnosus CS25 and L. delbrueckii M and standard strain ATCC 8014 showed broad antimicrobial activity, and isolates CS25 (percentage of survival 6·9 % at pH 2·5, 5·1 % at pH 2·0) and L. plantarum CS23 (5·7 % at pH 2·5, 4·9 % at pH 2·0) have shown good tolerance to acidic pH. Isolate CS23 showed a good survival (14 %) after 2 h incubation in de Man, Rogosa and Sharpe (MRS) medium containing 3 % bile salts. Isolates CS23, CS25 and L. fermentum ASt1 could stimulate Caco-2 cells, human PBMC and THP-1 cells for a strong and varied immunomodulatory response in these cells. Though LGG showed poor antimicrobial activity as well as bile and acid tolerance, it was found to be the best binding strain tested. Child faecal isolate CS23 from the present study showed high binding ability (seventeen bacteria/Caco-2), high tolerance to acidic pH and bile salts and significant immunomodulation; therefore it is a good potential probiotic candidate.

Aims: To analyse the expression of EF-Tu in Lactobacillus strains with response to mucin exposure and its role in interfering with adhesion of enteropathogens to mucin. Methods and Results: The Lactobacillus strains were analysed for their ability to adhere to immobilized mucin in microtiter plates. Lactobacillus delbrueckii M and Lactobacillus plantarum CS24Á2 showed statistically significant adhesion to mucin, which was similar to Lactobacillus rhamnosus GG, the best binding probiotic strain. Lactobacillus rhamnosus GG, Lact. delbrueckii M, Lact. plantarum CS23 and Lact. plantarum CS24Á2 were able to effectively antagonize the adhesion of Escherichia coli and Salmonella enterica serovar Typhi to mucin. In the presence of Lactobacillus adhesin -EF-Tu, the adhesion of Lact. delbrueckii M and the strains of Lact. plantarum to mucin was significantly inhibited. Similarly, EF-Tu also reduced the adhesion of enteropathogens to mucin. Furthermore, the relative fold change in gene expression analysis showed significant up-regulation of EF-Tu gene in the strains of Lact. plantarum and Lact. delbrueckii M when exposed to mucin for 3 h. Conclusions: The study shows the significant role of EF-Tu in lactobacilli adhesion and enteropathogens inhibition. Significance and Impact of the Study: The study suggests EF-Tu as an important factor linked to the Lactobacillus adhesion as well as enteropathogen inhibition. Lactobacillus plantarum CS23 and Lact. plantarum CS24Á2 can be used as potential probiotic strains.