The effect of lactobacillus casei derived extracellular vesicles on the expression of toll-like receptor 2

Maryam Ebrahimi vargoorani,1 Mohammad hossein modarressi,2 Elahe motevaseli,3 Farzam vaziri,4 Seyed davar siadat,5,*

1. Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
2. Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
3. Department of Molecular Medicine, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Te
4. Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran.
5. Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran



The use of probiotics represents a promising strategy for human health. one of the most common probiotic strains belongs to the genera lactobacillus. among the species of lactobacillus, lactobacillus casei is one of the best-documented, considered to be a probiotic with industrial applications. it has beneficial effects on human health such as significant improvements in immunity (galdeano and perdigon 2006), allergies (kumar et al. 2013), cholesterol levels (kumar et al. 2013). some studies have shown that l. casei improves the pattern of gut microbiota (sharma and devi 2014). lactic acid bacteria, are widely applied in the food industry. therefore, the identification and determining the advantage of molecules derived from lactic acid bacteria can be used to develop a new generation of functional compounds. one of the molecular components produced by bacteria is extracellular vesicles (evs). evs are spherical bilayers lipid structure that are in the range of 20–500 nm in diameter. these structures generally consist of varied cargo, such as toxins, lipoproteins, nucleic acids, and communication signals, and have crucial role in affecting metabolic and immune system (brown et al. 2015). in gram-positive bacteria, production of evs has been discarded owing to the absence of an outer membrane and visualization problems for penetration into the cell wall. this study aimed to show that lactobacillus casei can produce evs with similar morphology and size to other bacteria. since evs are an important agent to mediate the expression of genes. in this scientific research, we have examined to find out the effect of evs derived from l. casei on the expression of tlr2.


L. casei (atcc 393 strains) were obtained from the iranian biological resource center (tehran, iran). the bacteria were cultured in de man, rogosa and sharpe agar (mrs) (sigma-aldrich). in order to obtain more biomasses, a large volume of bacteria was cultured at 37°c for 24 hours in mrs broth. the evs were purified from the conditioned medium of l. casei using ultracentrifugation. physicochemical characteristics of these vesicles were compared using electron microscopy images, dynamic light scattering (dls) analyzer, and sds-page procedure. the caco2 cells were treated with different concentrations of purified evs.


The electron microscopy showed spherical vesicles that had an average diameter of 200nm. the extracted protein content was 2.4 in the ultracentrifugation method. also, protein bands of evs were identified in the range of 10-200 kd by sds-page. the dls analysis revealed populations of approximately 200 nm. the zeta potentials of the isolated vesicles were −0.5. it was determined that the evs of this bacterium at concentrations of 150 μg / ml had no significant effect on the expression of tlr2 gene expression in comparison with the control (sucrose), whereas the expression of this gene in treatment of evs at concentrations of 50 and 100 μg / ml decreased.


After extraction and evaluation of the physicochemical properties of l. casei derived evs, the induced effects of its vesicles on the expression of the tlr2 gene, we suggest that evs could be a candidate for modulating inflammatory responses. it may have many more beneficial discoveries regarding the impact of probiotic bacteria evs in the host–bacteria interaction.


Lactobacillus casei , extracellular vesicles, toll like receptors