Human monocyte-derived dendritic cells from leukoreduction system chambers after plateletpheresis are functional in an in vitro co-culture assay with intestinal epithelial cells

Effect of the dietary supplement PERMEAPROTECT+ TOLERANCE© on gut permeability in a human co-culture epithelial and immune cells model

Background and objective

The leaky gut syndrome is characterized by an intestinal hyperpermeability observed in multiple chronic disorders. Alterations of the gut barrier are associated with translocation of bacterial components increasing inflammation, oxidative stress and eventually dysfunctions of cellular interactions at the origin pathologies. Therapeutic and/or preventive approaches have to focus on the identification of novel targets to improve gut homeostasis. In this context, this study aims to identify the role of PERMEAPROTECT + TOLERANE©, known as PERMEA, a food complement composed of a combination of factors (including l-Glutamine) known to improve gut physiology.

Methods

We tested the effects of PERMEA or l-Glutamine alone (as reference) on gut permeability (FITC dextran method, expression of tight junctions) and its inflammatory/oxidative consequences (cytokines and redox assays, RT-qPCR) in a co-culture of human cells (peripheral blood mononuclear cells and intestinal epithelial cells) challenged with TNFα.

Results

PERMEA prevented intestinal hyperpermeability induced by inflammation. This was linked with its antioxidant and immunomodulatory properties showing a better efficacity than l-Glutamine alone on several parameters including permeability, global antioxidant charge and production of cytokines.

Conclusion

PERMEA is more efficient to restore intestinal physiology, reinforcing the concept that combination of food constituents could be used to prevent the development of numerous diseases.

Human in vitro blood barrier models: architectures and applications

Blood barriers serve as key points of transport for essential molecules as well as lines of defense to protect against toxins. In vitro modeling of these barriers is common practice in the study of their physiology and related diseases. This review describes a common method of using an adaptable, low cost, semipermeable, suspended membrane to experimentally model three blood barriers in the human body: the blood-brain barrier (BBB), the gut-blood barrier (GBB), and the air-blood barrier (ABB). The GBB and ABB both protect from the outside environment, while the BBB protects the central nervous system from potential neurotoxic agents in the blood. These barriers share several commonalities, including the formation of tight junctions, polarized cellular monolayers, and circulatory system contact. Cell architectures used to mimic barrier anatomy as well as applications to study function, dysfunction, and response provide an overview of the versatility enabled by these cultural systems.

Lactobacillus rhamnosus postbiotic-induced immunomodulation as safer alternative to the use of live bacteria

Many attempts have been made to search for safer immunomodulatory agents that enhance the immune response and reduce the number and severity of infections in at-risk populations. The use of postbiotics, non-viable microbial cells or cell fractions that confer a health benefit to the consumer, represents a safe and attractive way to modulate and enhance the immune function in order to improve human health. Therefore, the aim of this work is to evaluate the immunoregulatory effect of Lactobacillus rhamnosus CRL1505 postbiotics in a complex culture system using human intestinal epithelial cells (IECs) and dendritic cells (DCs) differentiated from peripheral blood mononuclear cells. First, we demonstrated that L. rhamnosus CRL1505 differentially modulate human IECs and DCs after the challenge with the TLR4 agonist LPS. The CRL1505 strain down-regulated CD40, CD80 and CD86 expression in DCs, and increased their production of TNF-α, IL-1β, IL-6 and IL-10. Interestingly, the non-viable strain was able to modulate the immune response of both types of human cells. Then, we showed that cell wall (CW1505) and peptidoglycan (PG1505) from L. rhamnosus CRL1505 modulated TLR4-triggered immune response in IECs and DCs. Of interest, CW1505 showed a strong stimulatory effect while the PG1505 presented immune characteristics that were more similar to viable and non-viable CRL1505. To date, several molecules of immunobiotics were identified, that can be connected to specific host-responses. We hereby demonstrated that peptidoglycan of L. rhamnosus CRL1505 is a key molecule for the immunobiotic properties of this strain in human IECs and DCs. Likewise, the result of these studies could provide predictive tools for the in vivo efficacy of postbiotics and the scientific basis for their future applications in immunocompromised patients.

Characterization of peripheral blood mononuclear cells isolated using two kinds of leukocyte filters

OBJECTIVE

The objective of this study was to compare the activity and biological function of leukocytes isolated using apheresis platelet leukoreduction system chambers (LRSC), whole blood leukoreduction filters (LRF), and leukocytes in unfiltered peripheral whole blood (WB).

METHODS

Peripheral blood mononuclear cells (PBMCs) and granulocytes were obtained by density gradient centrifugation using recovery filters and WB. Flow cytometry was used to detect the activity, phenotype, and apoptosis ratio of each cell subtype.

RESULTS

The proportion of lymphocytes obtained from PBMCs was similar when using the two different filters as compared to traditional isolation; however, there were significant differences between the monocytes and granulocytes. The phenotypic frequency of lymphocytes was similar, but the apoptosis rate of lymphocytes from the two filters was slightly higher. Additionally, monocytes isolated via the three sources were able to be induced into dendritic cells expressing specific molecules; Granulocytes isolated from the LRF showed a lower purity and a higher level of apoptosis than granulocytes isolated from the WB.

CONCLUSION

Compared with WB, the PBMCs isolated from the filters used in our blood center had no statistical difference in their activity and biological function, but they did differ in the proportion and quantity of monocytes and granulocytes. Our results show that the two filters can be used as an alternative method to collect leukocytes, which solves the problem of an insufficient blood supply for clinical and basic science research. Thus, these filters have significant value beyond their practical use in clinics.

Alternative RNA splicing of leucocyte tissue transglutaminase in coeliac disease

Tissue transglutaminase is a ubiquitous and multifunctional protein that contributes to several processes such as apoptosis/survival, efferocytosis, inflammation and tissue repairing under physiological and pathological conditions. Several activities can be associated with well-established functional domains; in addition, four RNA alternative splice variants have been described, characterized by sequence divergences and residues deletion at the C-terminal domains. Tissue transglutaminase is recognized as the central player in the physiopathology of coeliac disease (CD) mainly through calcium-dependent enzymatic activities. It can be hypothesized that differential regulation of tissue transglutaminase splice variants expression in persons with CD contributes to pathology by altering the protein functionality. We characterized the expression pattern of RNA alternative splice variants by RT-PCR in peripheral cells from patients with CD under free gluten diet adhesion; we considered inflammatory parameters and specific antibodies as markers of the stage of disease. We found significant higher expression of both the full length and the shortest C-truncated splice variants in leucocytes from patients with CD in comparison with healthy individuals. As tissue transglutaminase expression and canonical enzymatic activity are linked to inflammation, we studied the RNA expression of inflammatory cytokines in peripheral leucocytes of persons with CD in relation with splice variants expression; interestingly, we found that recently diagnosed patients showed significant correlation between both the full length and the shortest alternative spliced variants with IL-1 expression. Our results points that regulation of alternative splicing of tissue transglutaminase could account for the complex physiopathology of CD.

Lactobacillus delbrueckii subsp lactis CIDCA 133 modulates response of human epithelial and dendritic cells infected with Bacillus cereus

It is known that probiotic microorganisms are able to modulate pathogen virulence. This ability is strain dependent and involves multiple interactions between microorganisms and relevant host's cell populations. In the present work we focus on the effect of a potentially probiotic lactobacillus strain (Lactobacillus delbrueckii subsp. lactis CIDCA 133) in an in vitro model of Bacillus cereus infection. Our results showed that infection of intestinal epithelial HT-29 cells by B. cereus induces nuclear factor kappa B (NF-κB) pathway. Noteworthy, the presence of strain L. delbrueckii subsp.lactis CIDCA 133 increases stimulation. However, B. cereus-induced interleukin (IL)-8 production by epithelial cells is partially abrogated by L. delbrueckii subsp. lactis CIDCA 133. These findings suggest that signalling pathways other than that of NF-κB are involved. In a co-culture system (HT-29 and monocyte-derived dendritic cells), B. cereus was able to translocate from the epithelial (upper) to the dendritic cell compartment (lower). This translocation was partially abrogated by the presence of lactobacilli in the upper compartment. In addition, infection of epithelial cells in the co-culture model, led to an increase in the expression of CD86 by dendritic cells. This effect could not be modified in the presence of lactobacilli. Interestingly, infection of enterocytes with B. cereus triggers production of proinflammatory cytokines by dendritic cells (IL-8, IL-6 and tumour necrosis factor alpha (TNF-α)). The production of TNF-α (a protective cytokine in B. cereus infections) by dendritic cells was increased in the presence of lactobacilli. The present work demonstrates for the first time the effect of L. delbrueckii subsp. lactis CIDCA 133, a potentially probiotic strain, in an in vitro model of B. cereus infection. The presence of the probiotic strain modulates cell response both in infected epithelial and dendritic cells thus suggesting a possible beneficial effect of selected lactobacilli strains on the course of B. cereus infection.

MUC5B silencing reduces chemo-resistance of MCF-7 breast tumor cells and impairs maturation of dendritic cells

Mucins participate in cancer progression by regulating cell growth, adhesion, signaling, apoptosis or chemo-resistance to drugs. The secreted mucin MUC5B, the major component of the respiratory tract mucus, is aberrantly expressed in breast cancer, where it could constitute a cancer biomarker. In this study we evaluated the role of MUC5B in breast cancer by gene silencing the MUC5B expression with short hairpin RNA on MCF-7 cells. We found that MUC5B-silenced MCF-7 cells have a reduced capacity to grow, adhere and form cell colonies. Interestingly, MUC5B knock-down increased the sensitivity to death induced by chemotherapeutic drugs. We also show that MUC5B silencing impaired LPS-maturation of DCs, and production of cytokines. Furthermore, MUC5B knock-down also influenced DC-differentiation and activation since it resulted in an upregulation of IL-1β, IL-6 and IL-10, cytokines that might be involved in cancer progression. Thus, MUC5B could enhance the production of LPS-induced cytokines, suggesting that the use of MUC5B-based cancer vaccines combined with DC-maturation stimuli, could favor the induction of an antitumor immune response.

Kefir-isolated bacteria and yeasts inhibit Shigella flexneri invasion and modulate pro-inflammatory response on intestinal epithelial cells

The aim of this work was to evaluate the ability of a kefir-isolated microbial mixture containing three bacterial and two yeast strains (MM) to protect intestinal epithelial cells against Shigella flexneri invasion, as well as to analyse the effect on pro-inflammatory response elicited by this pathogen. A significant decrease in S. flexneri strain 72 invasion was observed on both HT-29 and Caco-2 cells pre-incubated with MM. Pre-incubation with the individual strains Saccharomyces cerevisiae CIDCA 8112 or Lactococcus lactis subsp. lactis CIDCA 8221 also reduced the internalisation of S. flexneri into HT-29 cells although in a lesser extent than MM. Interestingly, Lactobacillus plantarum CIDCA 83114 exerted a protective effect on the invasion of Caco-2 and HT-29 cells by S. flexneri. Regarding the pro-inflammatory response on HT-29 cells, S. flexneri infection induced a significant activation of the expression of interleukin 8 (IL-8), chemokine (C-C motif) ligand 20 (CCL20) and tumour necrosis factor alpha (TNF-α) encoding genes (P<0.05), whereas incubation of cells with MM did not induce the expression of any of the mediators assessed. Interestingly, pre-incubation of HT-29 monolayer with MM produced an inhibition of S. flexneri-induced IL-8, CCL20 and TNF-α mRNA expression. In order to gain insight on the effect of MM (or the individual strains) on this pro-inflammatory response, a series of experiments using a HT-29-NF-κB-hrGFP reporter system were performed. Pre-incubation of HT-29-NF-κB-hrGFP cells with MM significantly dampened Shigella-induced activation. Our results showed that the contribution of yeast strain Kluyveromyces marxianus CIDCA 8154 seems to be crucial in the observed effect. In conclusion, results presented in this study demonstrate that pre-treatment with a microbial mixture containing bacteria and yeasts isolated from kefir, resulted in inhibition of S. flexneri internalisation into human intestinal epithelial cells, along with the inhibition of the signalling via NF-κB that in turn led to the attenuation of the inflammatory response.

Cell Systems to Investigate the Impact of Polyphenols on Cardiovascular Health

Polyphenols are a diverse group of micronutrients from plant origin that may serve as antioxidants and that contribute to human health in general. More specifically, many research groups have investigated their protective effect against cardiovascular diseases in several animal studies and human trials. Yet, because of the excessive processing of the polyphenol structure by human cells and the residing intestinal microbial community, which results in a large variability between the test subjects, the exact mechanisms of their protective effects are still under investigation. To this end, simplified cell culture systems have been used to decrease the inter-individual variability in mechanistic studies. In this review, we will discuss the different cell culture models that have been used so far for polyphenol research in the context of cardiovascular diseases. We will also review the current trends in cell culture research, including co-culture methodologies. Finally, we will discuss the potential of these advanced models to screen for cardiovascular effects of the large pool of bioactive polyphenols present in foods and their metabolites.

Leukoreduction system chambers are an efficient, valid, and economic source of functional monocyte-derived dendritic cells and lymphocytes

The demand for human monocyte-derived dendritic cells (moDCs), as well as for primary human B and T lymphocytes for immunological research purposes has been increased in recent years. Classically, these monocytes are isolated from blood, leukapheresis products or buffy coats of healthy donors by plastic adherence of peripheral blood mononuclear cells (PBMCs), followed by stimulation with granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, while lymphocytes are usually isolated from the non-adherent fraction (NAF) by magnetic cell sorting. However, donor-blood is a limited resource and not every blood bank offers leukapheresis products or buffy coats for laboratory use. Additionally, a leukapheresis is very expensive and also the generation/isolation of cells is time- and cost-intensive. To overcome some of these obstacles, we evaluated if low-cost leukoreduction system chambers (LRSCs), which arise after routine donor plateletpheresis procedures, and are usually discarded, would be an alternative and appropriate source of PBMCs to generate moDCs and to isolate lymphocytes. By analyzing the number and phenotype of immature and mature dendritic cells (DCs), as well as of B and T lymphocytes derived from LRSCs, we found all cells to be of high quantity and quality. Further investigations on DCs comprising transwell migration assays, allogeneic mixed lymphocyte reactions (MLR), cytokine secretion assays, and cytotoxic T cell induction assays revealed high migratory, as well as stimulatory capacity of these cells. In addition, DCs and T cells were efficiently electroporated with mRNA and showed characteristic cytokine production after co-culture, demonstrating LRSCs as an efficient, valid, and economic source for generation of moDCs and lymphocytes for research purposes.